1.
Louisiana
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Louisiana is a state located in the southern region of the United States. Louisiana is the 31st most extensive and the 25th most populous of the 50 United States and its capital is Baton Rouge and largest city is New Orleans. Louisiana is the state in the U. S. with political subdivisions termed parishes. The largest parish by population is East Baton Rouge Parish, Louisiana is bordered by Arkansas to the north, Mississippi to the east, Texas to the west, and the Gulf of Mexico to the south. Much of the lands were formed from sediment washed down the Mississippi River, leaving enormous deltas and vast areas of coastal marsh. These contain a rich southern biota, typical examples include birds such as ibis, there are also many species of tree frogs, and fish such as sturgeon and paddlefish. In more elevated areas, fire is a process in the landscape. These support a large number of plant species, including many species of orchids. Louisiana has more Native American tribes than any other state, including four that are federally recognized, ten that are state recognized. Before the American purchase of the territory in 1803, the current Louisiana State had been both a French colony and for a period, a Spanish one. In addition, colonists imported numerous African people as slaves in the 18th century, many came from peoples of the same region of West Africa, thus concentrating their culture. Louisiana was named after Louis XIV, King of France from 1643 to 1715, when René-Robert Cavelier, Sieur de La Salle claimed the territory drained by the Mississippi River for France, he named it La Louisiane. The suffix -ana is a Latin suffix that can refer to information relating to an individual, subject. Thus, roughly, Louis + ana carries the idea of related to Louis, the Gulf of Mexico did not exist 250 million years ago when there was but one supercontinent, Pangea. As Pangea split apart, the Atlantic Ocean and Gulf of Mexico opened, Louisiana slowly developed, over millions of years, from water into land, and from north to south. The oldest rocks are exposed in the north, in such as the Kisatchie National Forest. The oldest rocks date back to the early Tertiary Era, some 60 million years ago, the history of the formation of these rocks can be found in D. Spearings Roadside Geology of Louisiana. The sediments were carried north to south by the Mississippi River
2.
Extratropical cyclone
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Extratropical cyclones are capable of producing anything from cloudiness and mild showers to heavy gales, thunderstorms, blizzards, and tornadoes. These types of cyclones are defined as large scale low pressure systems that occur in the middle latitudes of the Earth. In contrast with tropical cyclones, extratropical cyclones produce rapid changes in temperature and dew point along broad lines, called weather fronts, the term cyclone applies to numerous types of low pressure areas, one of which is the extratropical cyclone. The descriptor extratropical signifies that this type of cyclone generally occurs outside the tropics and they are termed mid-latitude cyclones if they form within those latitudes, or post-tropical cyclones if a tropical cyclone has intruded into the mid latitudes. Weather forecasters and the public often describe them simply as depressions or lows. Terms like frontal cyclone, frontal depression, frontal low, extratropical low, non-tropical low, Extratropical cyclones are classified mainly as baroclinic, because they form along zones of temperature and dewpoint gradient known as frontal zones. They can become barotropic late in their cycle, when the distribution of heat around the cyclone becomes fairly uniform with its radius. Extratropical cyclones form anywhere within the regions of the Earth. A study of extratropical cyclones in the Southern Hemisphere shows that between the 30th and 70th parallels, there are an average of 37 cyclones in existence during any 6-hour period, a separate study in the Northern Hemisphere suggests that approximately 234 significant extratropical cyclones form each winter. Extratropical cyclones form along linear bands of temperature/dewpoint gradient with significant vertical wind shear, initially, cyclogenesis, or low pressure formation, occurs along frontal zones near a favorable quadrant of a maximum in the upper level jetstream known as a jet streak. The favorable quadrants are usually at the rear and left front quadrants. The divergence causes air to rush out from the top of the air column and this in turn forces convergence in the low-level wind field and increased upward motion within the column. The increased upward motion causes atmospheric pressure at ground level to lower and this is because the upward air motion counteracts gravity, lessening the weight of the atmosphere in that location. The lowered pressure strengthens the cyclone, as the cyclone strengthens, the cold front sweeps towards the equator and moves around the back of the cyclone. Meanwhile, its associated warm front progresses more slowly, as the air ahead of the system is denser. Later, the cyclones occlude as the portion of the cold front overtakes a section of the warm front, forcing a tongue, or trowal. Eventually, the cyclone will become cold and begin to weaken. Atmospheric pressure can fall very rapidly when there are upper level forces on the system
3.
Bar (unit)
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The bar is a metric unit of pressure, but is not approved as part of the International System of Units. It is defined as equal to 100000 Pa, which is slightly less than the current average atmospheric pressure on Earth at sea level. The bar and the millibar were introduced by the Norwegian meteorologist Vilhelm Bjerknes, use of the bar is deprecated by some professional bodies in some fields. The International Astronomical Union also lists it under Non-SI units and symbols whose continued use is deprecated, as of 2004, the bar is legally recognized in countries of the European Union. Units derived from the bar include the megabar, kilobar, decibar, centibar, the notation bar, though deprecated by various bodies, represents gauge pressure, i. e. pressure in bars above ambient or atmospheric pressure. The bar is defined using the SI derived unit, pascal,1 bar ≡100000 Pa. Thus,1 bar is equal to,100 kPa 1×105 N/m21000000 Ba, notes,1 millibar =1 one-thousandth bar, or 1×10−3 bar 1 millibar =1 hectopascal. The word bar has its origin in the Greek word βάρος, the units official symbol is bar, the earlier symbol b is now deprecated and conflicts with the use of b denoting the unit barn, but it is still encountered, especially as mb to denote the millibar. Between 1793 and 1795, the bar was used for a unit of weight in an early version of the metric system. Atmospheric air pressure is given in millibars where standard sea level pressure is defined as 1013 mbar,101.3,1.013 bar. Despite the millibar not being an SI unit, meteorologists and weather reporters worldwide have long measured air pressure in millibars as the values are convenient, for example, the weather office of Environment Canada uses kilopascals and hectopascals on their weather maps. In contrast, Americans are familiar with the use of the millibar in US reports of hurricanes, in fresh water, there is an approximate numerical equivalence between the change in pressure in decibars and the change in depth from the water surface in metres. Specifically, an increase of 1 decibar occurs for every 1.019716 m increase in depth, in sea water with respect to the gravity variation, the latitude and the geopotential anomaly the pressure can be converted into meters depth according to an empirical formula. As a result, decibars are commonly used in oceanography, many engineers worldwide use the bar as a unit of pressure because, in much of their work, using pascals would involve using very large numbers. In the automotive field, turbocharger boost is often described in bars outside the USA), unicode has characters for mb and bar, but they exist only for compatibility with legacy Asian encodings and are not intended to be used in new documents. The kilobar, equivalent to 100 MPa, is used in geological systems. Bar and bara are sometimes used to indicate absolute pressures and bar and this usage is deprecated and fuller descriptions such as gauge pressure of 2 bar or 2 bar gauge are recommended.0 Unported License but not under the GFDL. Non-SI units accepted for use with the SI
4.
Pascal (unit)
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The pascal is the SI derived unit of pressure used to quantify internal pressure, stress, Youngs modulus and ultimate tensile strength. It is defined as one newton per square meter and it is named after the French polymath Blaise Pascal. Common multiple units of the pascal are the hectopascal which is equal to one millibar, the unit of measurement called standard atmosphere is defined as 101,325 Pa and approximates to the average pressure at sea-level at the latitude 45° N. Meteorological reports typically state atmospheric pressure in hectopascals, the unit is named after Blaise Pascal, noted for his contributions to hydrodynamics and hydrostatics, and experiments with a barometer. The name pascal was adopted for the SI unit newton per square metre by the 14th General Conference on Weights, one pascal is the pressure exerted by a force of magnitude one newton perpendicularly upon an area of one square metre. The unit of measurement called atmosphere or standard atmosphere is 101325 Pa and this value is often used as a reference pressure and specified as such in some national and international standards, such as ISO2787, ISO2533 and ISO5024. In contrast, IUPAC recommends the use of 100 kPa as a standard pressure when reporting the properties of substances, geophysicists use the gigapascal in measuring or calculating tectonic stresses and pressures within the Earth. Medical elastography measures tissue stiffness non-invasively with ultrasound or magnetic resonance imaging, in materials science and engineering, the pascal measures the stiffness, tensile strength and compressive strength of materials. In engineering use, because the pascal represents a small quantity. The pascal is also equivalent to the SI unit of energy density and this applies not only to the thermodynamics of pressurised gases, but also to the energy density of electric, magnetic, and gravitational fields. In measurements of sound pressure, or loudness of sound, one pascal is equal to 94 decibels SPL, the quietest sound a human can hear, known as the threshold of hearing, is 0 dB SPL, or 20 µPa. The airtightness of buildings is measured at 50 Pa, the units of atmospheric pressure commonly used in meteorology were formerly the bar, which was close to the average air pressure on Earth, and the millibar. Since the introduction of SI units, meteorologists generally measure pressures in hectopascals unit, exceptions include Canada and Portugal, which use kilopascals. In many other fields of science, the SI is preferred, many countries also use the millibar or hectopascal to give aviation altimeter settings. In practically all fields, the kilopascal is used instead. Centimetre of water Metric prefix Orders of magnitude Pascals law
5.
United States dollar
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The United States dollar is the official currency of the United States and its insular territories per the United States Constitution. It is divided into 100 smaller cent units, the circulating paper money consists of Federal Reserve Notes that are denominated in United States dollars. The U. S. dollar was originally commodity money of silver as enacted by the Coinage Act of 1792 which determined the dollar to be 371 4/16 grain pure or 416 grain standard silver, the currency most used in international transactions, it is the worlds primary reserve currency. Several countries use it as their currency, and in many others it is the de facto currency. Besides the United States, it is used as the sole currency in two British Overseas Territories in the Caribbean, the British Virgin Islands and Turks and Caicos Islands. A few countries use the Federal Reserve Notes for paper money, while the country mints its own coins, or also accepts U. S. coins that can be used as payment in U. S. dollars. After Nixon shock of 1971, USD became fiat currency, Article I, Section 8 of the U. S. Constitution provides that the Congress has the power To coin money, laws implementing this power are currently codified at 31 U. S. C. Section 5112 prescribes the forms in which the United States dollars should be issued and these coins are both designated in Section 5112 as legal tender in payment of debts. The Sacagawea dollar is one example of the copper alloy dollar, the pure silver dollar is known as the American Silver Eagle. Section 5112 also provides for the minting and issuance of other coins and these other coins are more fully described in Coins of the United States dollar. The Constitution provides that a regular Statement and Account of the Receipts and that provision of the Constitution is made specific by Section 331 of Title 31 of the United States Code. The sums of money reported in the Statements are currently being expressed in U. S. dollars, the U. S. dollar may therefore be described as the unit of account of the United States. The word dollar is one of the words in the first paragraph of Section 9 of Article I of the Constitution, there, dollars is a reference to the Spanish milled dollar, a coin that had a monetary value of 8 Spanish units of currency, or reales. In 1792 the U. S. Congress passed a Coinage Act, Section 20 of the act provided, That the money of account of the United States shall be expressed in dollars, or units. And that all accounts in the offices and all proceedings in the courts of the United States shall be kept and had in conformity to this regulation. In other words, this act designated the United States dollar as the unit of currency of the United States, unlike the Spanish milled dollar the U. S. dollar is based upon a decimal system of values. Both one-dollar coins and notes are produced today, although the form is significantly more common
6.
Guatemala
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With an estimated population of around 15.8 million, it is the most populated state in Central America. Guatemala is a democracy, its capital and largest city is Nueva Guatemala de la Asunción. The territory of modern Guatemala once formed the core of the Maya civilization, most of the country was conquered by the Spanish in the 16th century, becoming part of the viceroyalty of New Spain. Guatemala attained independence in 1821 as part of the Federal Republic of Central America, from the mid to late 19th century, Guatemala experienced chronic instability and civil strife. Beginning in the early 20th century, it was ruled by a series of dictators backed by the United Fruit Company, in 1944, authoritarian leader Jorge Ubico was overthrown by a pro-democratic military coup, initiating a decade-long revolution that led to sweeping social and economic reforms. A U. S. -backed military coup in 1954 ended the revolution, from 1960 to 1996, Guatemala endured a bloody civil war fought between the US-backed government and leftist rebels, including genocidal massacres of the Maya population perpetrated by the military. As of 2014, Guatemala ranks 31st of 33 Latin American and Caribbean countries in terms of the Human Development Index, Guatemalas abundance of biologically significant and unique ecosystems includes a large number of endemic species and contributes to Mesoamericas designation as a biodiversity hotspot. The country is known for its rich and distinct culture. The name Guatemala comes from the Nahuatl word Cuauhtēmallān, or place of many trees and this was the name the Tlaxcaltecan soldiers who accompanied Pedro de Alvarado during the Spanish Conquest gave to this territory. The first evidence of habitation in Guatemala dates back to 12,000 BC. Evidence, such as obsidian arrowheads found in parts of the country. There is archaeological proof that early Guatemalan settlers were hunters and gatherers, pollen samples from Petén and the Pacific coast indicate that maize cultivation had been developed by 3500 BC. Sites dating back to 6500 BC have been found in the Quiché region in the Highlands, archaeologists divide the pre-Columbian history of Mesoamerica into the Preclassic period, the Classic period, and the Postclassic period. Until recently, the Preclassic was regarded as a period, with small villages of farmers who lived in huts. This period is characterized by urbanisation, the emergence of independent city-states and this lasted until approximately 900 AD, when the Classic Maya civilization collapsed. The Maya abandoned many of the cities of the lowlands or were killed off by a drought-induced famine. The cause of the collapse is debated, but the Drought Theory is gaining currency, supported by such as lakebeds, ancient pollen. A series of prolonged droughts, among other such as overpopulation, in what is otherwise a seasonal desert is thought to have decimated the Maya
7.
Gulf Coast of the United States
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The Gulf Coast of the United States is the coastline along which the Southern United States meets the Gulf of Mexico. The coastal states that have a shoreline on the Gulf of Mexico are Texas, Louisiana, Mississippi, Alabama, and Florida, the economy of the Gulf Coast area is dominated by industries related to energy, petrochemicals, fishing, aerospace, agriculture, and tourism. The Gulf Coast is made of many inlets, bays, the coast is also intersected by numerous rivers, the largest of which is the Mississippi River. Much of the land along the Gulf Coast is, or was and these landforms protect numerous bays and inlets providing as a barrier to oncoming waves. The central part of the Gulf Coast, from eastern Texas through Louisiana, the eastern part of the Gulf Coast, predominantly Florida, is dotted with many bays and inlets. The Gulf Coast climate is humid subtropical for the most part, although the tip of Florida. Much of the year is warm to hot along the Gulf Coast, while the 3 winters months bring periods of cool, the area is vulnerable to hurricanes as well as floods and severe thunderstorms. Tornadoes are infrequent at the coast but do occur, however the frequency at which they occur in inland portions of Gulf Coast states is much greater. Earthquakes are extremely rare to the area, but a surprising 6.0 earthquake in the Gulf of Mexico on September 10,2006, the Gulf Coast is a major center of economic activity. The marshlands along the Louisiana and Texas coasts provide breeding grounds, the Port of South Louisiana and the Port of Houston are two of the ten busiest ports in the world by cargo volume. As of 2004, seven of the top ten busiest ports in the U. S. are on the Gulf Coast. The discovery of oil and gas deposits along the coast and offshore, the coast contains nearly 4,000 oil platforms. S. Before Europeans arrived in the region, the region was home to several kingdoms that had extensive trade networks with empires such as the Aztecs. Shark and alligator teeth and shells from the Gulf have been found as far north as Ohio, the first Europeans to settle the Gulf Coast were primarily the French and the Spanish. The Louisiana Purchase and the Texas Revolution made the Gulf Coast a part of the United States during the first half of the 19th century. As the U. S. population continued to expand its frontiers westward, the development of sugar and cotton production allowed the South to prosper. Two major events were turning points in the history of the Gulf Coast region. The first was the American Civil War, which caused damage to some economic sectors in the South
8.
Florida Panhandle
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Its eastern boundary is arbitrarily defined. As is the case with the other eight U. S. states that have panhandles and these western counties also lie in the Central Time Zone, while the rest of the state is in the Eastern Time Zone. References to the Panhandle may also include some or all of eight counties immediately east of the Apalachicola known as the Big Bend region, the largest city in the Panhandle is Tallahassee, the state capital, population 188,107. However, the largest population grouping is the Pensacola Metropolitan Area with a population of 474,081, the total population of the Panhandle, as of the 2010 Census, was 1,407,925. Earlier designations include Playground of the Gulfcoast and the Miracle Strip and it is usually not considered a part of the Emerald Coast, which lies directly adjacent to the west. It is formed by the junction of several rivers, including the Chattahoochee and the Flint, where the boundaries of Alabama, Georgia, from there, it flows due south to the town of Apalachicola. Interstate 10 is the major interstate highway in the Panhandle, connecting the extreme west with North Florida. Other older east–west routes include U. S. Highway 90, important north–south routes west of the Apalachicola River include U. S. Highway 29, U. S. Highway 331, and U. S. Highway 231, all linking to Alabama and Interstate 65. State Road 20 stretches from Niceville to Tallahassee, the major railroad line through the Panhandle, running from Pensacola to Jacksonville, is owned by CSX railroad. Regional short-line railroads serving the Panhandle are the Alabama and Gulf Coast Railway, the Bay Line Railroad, throughout the 19th century, the Panhandle was sparsely populated, dotted in places with small farming communities, none of which had as many as a thousand residents. It was natural for West Floridians to feel that they had more in common with their neighbors in Alabama than with the residents of the peninsula. In 1821, Pensacola was the city in West Florida. In the 1850 census, the population of Pensacola was 2,164. In 1819, the convention of Alabama asked Congress to include West Florida in their new state. In 1826, the Pensacola Gazette published a number of letters advocating annexation to Alabama, in 1840, a public meeting in Pensacola produced a demand that West Florida be united with Alabama. In 1856, advocates of annexation were able to get a bill passed by the Legislature authorizing a referendum on the issue, the Pensacola Gazette reported that annexation is desired by a large majority of the people of the area. In 1858, the Alabama Legislature unsuccessfully tried to open negotiations with Florida on the subject, in that year, the Alabama Legislature approved a joint resolution authorizing their Governor to negotiate with the Governor of Florida about the annexation of West Florida. An offer of one million dollars in Alabama state bonds, paying 8 percent interest for thirty years, was included, both states appointed commissioners to make detailed recommendations on the matter
9.
Ohio River Valley
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The Ohio River, which streams westward from Pittsburgh, Pennsylvania, to Cairo, Illinois, is the largest tributary, by volume, of the Mississippi River in the United States. The 981-mile river flows through or along the border of six states, through its largest tributary, the Tennessee River, the basin includes many of the states of the southeastern U. S. It is the source of drinking water for three million people and it is named in Iroquoian or Seneca, Ohi, yó, lit. Good River or Shawnee, Pelewathiipi and Spelewathiipi, the river had great significance in the history of the Native Americans, as numerous civilizations formed along its valley. For thousands of years, Native Americans used the river as a major transportation, in 1669, René-Robert Cavelier, Sieur de La Salle led a French expedition to the Ohio River, becoming the first Europeans to see it. After European-American settlement, the served as a border between present-day Kentucky and Indian Territories. It was a transportation route for pioneers during the westward expansion of the early U. S. In his Notes on the State of Virginia published in 1781–82, Thomas Jefferson stated and its current gentle, waters clear, and bosom smooth and unbroken by rocks and rapids, a single instance only excepted. During the 19th century, the river was the boundary of the Northwest Territory. Where the river was narrow, it was the way to freedom for thousands of slaves escaping to the North, many helped by free blacks and whites of the Underground Railroad resistance movement. The Ohio River is a transition area, as its water runs along the periphery of the humid subtropical. It is inhabited by fauna and flora of both climates, in winter, it regularly freezes over at Pittsburgh but rarely further south toward Cincinnati and Louisville. At Paducah, Kentucky, in the south, near the Ohios confluence with the Mississippi, Paducah was founded there because it is the northernmost ice-free reach of the Ohio. The Ohio River is formed by the confluence of the Allegheny and Monongahela rivers at Point State Park in Pittsburgh, from there, it flows northwest through Allegheny and Beaver counties, before making an abrupt turn to the south-southwest at the West Virginia–Ohio–Pennsylvania triple-state line. From there, it forms the border between West Virginia and Ohio, upstream of Wheeling, West Virginia, the river then follows a roughly southwest and then west-northwest course until Cincinnati, before bending to a west-southwest course for most of its length. The course forms the borders of West Virginia and Kentucky. The Ohio drains parts of 15 states in four regions, northeast New York, a small area of the southern border along the headwaters of the Allegheny. Pennsylvania, a corridor from the corner to north central border
10.
Ontario
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Ontario, one of the 13 provinces and territories of Canada, is located in east-central Canada. It is Canadas most populous province by a margin, accounting for nearly 40 percent of all Canadians. Ontario is fourth-largest in total area when the territories of the Northwest Territories and it is home to the nations capital city, Ottawa, and the nations most populous city, Toronto. There is only about 1 km of land made up of portages including Height of Land Portage on the Minnesota border. Ontario is sometimes divided into two regions, Northern Ontario and Southern Ontario. The great majority of Ontarios population and arable land is located in the south, in contrast, the larger, northern part of Ontario is sparsely populated with cold winters and is heavily forested. The province is named after Lake Ontario, a thought to be derived from Ontarí, io, a Huron word meaning great lake, or possibly skanadario. Ontario has about 250,000 freshwater lakes, the province consists of three main geographical regions, The thinly populated Canadian Shield in the northwestern and central portions, which comprises over half the land area of Ontario. Although this area mostly does not support agriculture, it is rich in minerals and in part covered by the Central and Midwestern Canadian Shield forests, studded with lakes, Northern Ontario is subdivided into two sub-regions, Northwestern Ontario and Northeastern Ontario. The virtually unpopulated Hudson Bay Lowlands in the north and northeast, mainly swampy. Southern Ontario which is further sub-divided into four regions, Central Ontario, Eastern Ontario, Golden Horseshoe, the highest point is Ishpatina Ridge at 693 metres above sea level located in Temagami, Northeastern Ontario. In the south, elevations of over 500 m are surpassed near Collingwood, above the Blue Mountains in the Dundalk Highlands, the Carolinian forest zone covers most of the southwestern region of the province. A well-known geographic feature is Niagara Falls, part of the Niagara Escarpment, the Saint Lawrence Seaway allows navigation to and from the Atlantic Ocean as far inland as Thunder Bay in Northwestern Ontario. Northern Ontario occupies roughly 87 percent of the area of the province. Point Pelee is a peninsula of Lake Erie in southwestern Ontario that is the southernmost extent of Canadas mainland, Pelee Island and Middle Island in Lake Erie extend slightly farther. All are south of 42°N – slightly farther south than the border of California. The climate of Ontario varies by season and location, the effects of these major air masses on temperature and precipitation depend mainly on latitude, proximity to major bodies of water and to a small extent, terrain relief. In general, most of Ontarios climate is classified as humid continental, Ontario has three main climatic regions
11.
1995 Atlantic hurricane season
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The 1995 Atlantic hurricane season was a highly active year that tied with 1887,2010,2011, and 2012 for having the third most number of named storms. The season produced twenty-one tropical cyclones, nineteen named storms, as well as eleven hurricanes, the season officially began on June 1 and ended on November 30, dates which conventionally delimit the period of each year when most tropical cyclones develop in the Atlantic basin. The first tropical cyclone, Hurricane Allison, developed on June 2, while the final storm, Hurricane Tanya. There were four particularly destructive hurricanes during the season, including Luis, Marilyn, Opal, hurricanes Luis and Marilyn both caused catastrophic damage in the Leeward Islands and Virgin Islands. The former storm was the first hurricane to affect those regions since Hurricane Hugo, Opal, the strongest and most intense storm of the season, causing devastation along portions of the Gulf Coast of the United States. Roxanne, a rare late-season major hurricane, caused significant damage when it made landfall in Quintana Roo, additionally, Erin produced moderate damage in Florida. Felix generated strong waves, causing beach erosion in the Northeastern United States. Iris caused flooding that left five deaths in the Lesser Antilles, collectively, the tropical cyclones of the season caused about $12.85 billion in damage and at least 182 deaths. At the seasons end,1995 ranked as the second most active in recorded history, tying 1887 and it is now the third most active season alongside 2010,2011, and 2012. Additionally, the 1950–2000 CSU average for a season is 9.6 named storms, of these 5.9 reach hurricane strength. In December 1994, CSU predicted that only 12 named storms would form and 8 of those would become hurricanes,3 major hurricanes were projected. CSU noted an above average due to expectations that the existing El Niño would dissipate. Additionally, the areas of the Sahara Desert were predicted to have the fourth or fifth rainiest season since 1970. A year with precipitation in this region usually correlates with an active Atlantic hurricane season. In April 1995, CSU revised their forecast, decreasing the number of named storms to 10, hurricanes to 6, however, in June, CSU reverted to their December forecast, which called for 12 named storms,8 hurricanes, and 3 major hurricanes. The forecast by the WRC in early 1995 was 10 named storms and 6 hurricanes, the Atlantic hurricane season officially began on June 1, and activity in 1995 began on the next day with the formation of Hurricane Allison on June 2. It was an average season in which 21 tropical depressions formed,19 of which attained tropical storm status. In addition, five tropical cyclones reached hurricane status, which was well above the 1950–2005 average of two per season
12.
Tropical cyclone
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Depending on its location and strength, a tropical cyclone is referred to by names such as hurricane, typhoon /taɪˈfuːn/, tropical storm, cyclonic storm, tropical depression, and simply cyclone. A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through the evaporation of water from the ocean surface and this energy source differs from that of mid-latitude cyclonic storms, such as noreasters and European windstorms, which are fueled primarily by horizontal temperature contrasts. The strong rotating winds of a tropical cyclone are a result of the conservation of momentum imparted by the Earths rotation as air flows inwards toward the axis of rotation. As a result, they form within 5° of the equator. Tropical cyclones are typically between 100 and 2,000 km in diameter, Tropical refers to the geographical origin of these systems, which form almost exclusively over tropical seas. Cyclone refers to their nature, with wind blowing counterclockwise in the Northern Hemisphere. The opposite direction of circulation is due to the Coriolis effect, in addition to strong winds and rain, tropical cyclones are capable of generating high waves, damaging storm surge, and tornadoes. They typically weaken rapidly over land where they are cut off from their energy source. For this reason, coastal regions are vulnerable to damage from a tropical cyclone as compared to inland regions. Heavy rains, however, can cause significant flooding inland, though their effects on human populations are often devastating, tropical cyclones can relieve drought conditions. They also carry heat away from the tropics and transport it toward temperate latitudes. Tropical cyclones are areas of low pressure in the troposphere. On Earth, the pressures recorded at the centers of tropical cyclones are among the lowest ever observed at sea level, the environment near the center of tropical cyclones is warmer than the surroundings at all altitudes, thus they are characterized as warm core systems. The near-surface wind field of a cyclone is characterized by air rotating rapidly around a center of circulation while also flowing radially inwards. At the outer edge of the storm, air may be nearly calm, however, due to the Earths rotation, as air flows radially inward, it begins to rotate cyclonically in order to conserve angular momentum. At an inner radius, air begins to ascend to the top of the troposphere and this radius is typically coincident with the inner radius of the eyewall, and has the strongest near-surface winds of the storm, consequently, it is known as the radius of maximum winds. Once aloft, air flows away from the center, producing a shield of cirrus clouds
13.
Pensacola, Florida
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Pensacola is the westernmost city in the Florida Panhandle and the county seat of Escambia County, in the U. S. state of Florida. As of the 2010 census, the city had a population of 51,923. Pensacola is the city of the Pensacola metropolitan area, which had an estimated 461,227 residents in 2012. Pensacola is a sea port on Pensacola Bay, which is protected by the island of Santa Rosa. The main campus of the University of West Florida is situated north of the city center, the area was originally inhabited by Muskogean peoples. The Pensacola people lived there at the time of European contact, Spanish explorer Tristán de Luna founded a short-lived settlement in 1559. In 1698 the Spanish established a presidio in the area, from which the city gradually developed. The area changed several times as European powers competed in North America. During Floridas British rule, fortifications were strengthened, other nicknames include Worlds Whitest Beaches, Cradle of Naval Aviation, Western Gate to the Sunshine State, Americas First Settlement, Emerald Coast, Red Snapper Capital of the World, and P-Cola. The original inhabitants of the Pensacola Bay area were Native American peoples, at the time of European contact, a Muskogean-speaking tribe known to the Spanish as the Pensacola lived in the region. This name was not recorded until 1677, but the tribe appears to be the source of the name Pensacola for the bay and thence the city. Creek people, also Muskogean-speaking, came regularly from present-day southern Alabama to trade, so the peoples were part of a broader regional and even continental network of relations. The best-known Pensacola culture site in terms of archeology is the Bottle Creek site and this site has at least 18 large earthwork mounds, five of which are arranged around a central plaza. Its main occupation was from 1250 AD to 1550 and it was a ceremonial center for the Pensacola people and a gateway to their society. This site would have had access by a dugout canoe. The areas written recorded history begins in the 16th century, with documentation by Spanish explorers who were the first Europeans to reach the area. The expeditions of Pánfilo de Narváez in 1528 and Hernando de Soto in 1539 both visited Pensacola Bay, the latter of which documented the name Bay of Ochuse. In 1559, Tristán de Luna y Arellano landed with some 1,500 people on 11 ships from Veracruz, Mexico
14.
Alabama
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Alabama is a state in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, Alabama is the 30th-most extensive and the 24th-most populous of the U. S. states. At nearly 1,500 miles, Alabama has one of the nations longest navigable inland waterways, Alabama is nicknamed the Yellowhammer State, after the state bird. Alabama is also known as the Heart of Dixie and the Cotton State, the state tree is the longleaf pine, and the state flower is the camellia. The largest city by population is Birmingham, which has long been the most industrialized city, the oldest city is Mobile, founded by French colonists in 1702 as the capital of French Louisiana. From the American Civil War until World War II, Alabama, like many states in the southern U. S. suffered economic hardship, like other southern states, Alabama legislators disenfranchised African Americans and many poor whites at the turn of the century. Following World War II, Alabama grew as the economy changed from one primarily based on agriculture to one with diversified interests. The state economy in the 21st century is based on management, automotive, finance, manufacturing, aerospace, mineral extraction, healthcare, education, retail, in the Alabama language, the word for a person of Alabama lineage is Albaamo. The word Alabama is believed to have come from the Alabama language, the words spelling varies significantly among historical sources. As early as 1702, the French called the tribe the Alibamon, other spellings of the name have included Alibamu, Alabamo, Albama, Alebamon, Alibama, Alibamou, Alabamu, Allibamou. Sources disagree on the words meaning, some scholars suggest the word comes from the Choctaw alba and amo. The meaning may have been clearers of the thicket or herb gatherers, the state has numerous place names of Native American origin. However, there are no correspondingly similar words in the Alabama language, an 1842 article in the Jacksonville Republican proposed it meant Here We Rest. This notion was popularized in the 1850s through the writings of Alexander Beaufort Meek, experts in the Muskogean languages have not found any evidence to support such a translation. Indigenous peoples of varying cultures lived in the area for thousands of years before the advent of European colonization, trade with the northeastern tribes by the Ohio River began during the Burial Mound Period and continued until European contact. The agrarian Mississippian culture covered most of the state from 1000 to 1600 AD, with one of its major centers built at what is now the Moundville Archaeological Site in Moundville, Alabama. This is the second-largest complex of the classic Middle Mississippian era, after Cahokia in present-day Illinois, Analysis of artifacts from archaeological excavations at Moundville were the basis of scholars formulating the characteristics of the Southeastern Ceremonial Complex. Contrary to popular belief, the SECC appears to have no links to Mesoamerican culture
15.
Tennessee
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Tennessee is a state located in the southeastern region of the United States. Tennessee is the 36th largest and the 17th most populous of the 50 United States, Tennessee is bordered by Kentucky and Virginia to the north, North Carolina to the east, Georgia, Alabama, and Mississippi to the south, and Arkansas and Missouri to the west. The Appalachian Mountains dominate the eastern part of the state, Tennessees capital and second largest city is Nashville, which has a population of 654,610. Memphis is the states largest city, with a population of 655,770, the state of Tennessee is rooted in the Watauga Association, a 1772 frontier pact generally regarded as the first constitutional government west of the Appalachians. What is now Tennessee was initially part of North Carolina, Tennessee was admitted to the Union as the 16th state on June 1,1796. Tennessee was the last state to leave the Union and join the Confederacy at the outbreak of the American Civil War in 1861, occupied by Union forces from 1862, it was the first state to be readmitted to the Union at the end of the war. Tennessee furnished more soldiers for the Confederate Army than any other state besides Virginia and this sharply reduced competition in politics in the state until after passage of civil rights legislation in the mid-20th century. This city was established to house the Manhattan Projects uranium enrichment facilities, helping to build the worlds first atomic bomb, Tennessees major industries include agriculture, manufacturing, and tourism. Poultry, soybeans, and cattle are the primary agricultural products, and major manufacturing exports include chemicals, transportation equipment. In the early 18th century, British traders encountered a Cherokee town named Tanasi in present-day Monroe County, the town was located on a river of the same name, and appears on maps as early as 1725. The meaning and origin of the word are uncertain, some accounts suggest it is a Cherokee modification of an earlier Yuchi word. It has been said to mean meeting place, winding river, according to ethnographer James Mooney, the name can not be analyzed and its meaning is lost. The modern spelling, Tennessee, is attributed to James Glen, the governor of South Carolina, the spelling was popularized by the publication of Henry Timberlakes Draught of the Cherokee Country in 1765. In 1788, North Carolina created Tennessee County, the county to be established in what is now Middle Tennessee. When a constitutional convention met in 1796 to organize a new out of the Southwest Territory. Other sources differ on the origin of the nickname, according to the Columbia Encyclopedia. Tennessee ties Missouri as the state bordering the most other states, the state is trisected by the Tennessee River. The highest point in the state is Clingmans Dome at 6,643 feet, Clingmans Dome, which lies on Tennessees eastern border, is the highest point on the Appalachian Trail, and is the third highest peak in the United States east of the Mississippi River
16.
Ohio River
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The Ohio River, which streams westward from Pittsburgh, Pennsylvania, to Cairo, Illinois, is the largest tributary, by volume, of the Mississippi River in the United States. The 981-mile river flows through or along the border of six states, through its largest tributary, the Tennessee River, the basin includes many of the states of the southeastern U. S. It is the source of drinking water for three million people and it is named in Iroquoian or Seneca, Ohi, yó, lit. Good River or Shawnee, Pelewathiipi and Spelewathiipi, the river had great significance in the history of the Native Americans, as numerous civilizations formed along its valley. For thousands of years, Native Americans used the river as a major transportation, in 1669, René-Robert Cavelier, Sieur de La Salle led a French expedition to the Ohio River, becoming the first Europeans to see it. After European-American settlement, the served as a border between present-day Kentucky and Indian Territories. It was a transportation route for pioneers during the westward expansion of the early U. S. In his Notes on the State of Virginia published in 1781–82, Thomas Jefferson stated and its current gentle, waters clear, and bosom smooth and unbroken by rocks and rapids, a single instance only excepted. During the 19th century, the river was the boundary of the Northwest Territory. Where the river was narrow, it was the way to freedom for thousands of slaves escaping to the North, many helped by free blacks and whites of the Underground Railroad resistance movement. The Ohio River is a transition area, as its water runs along the periphery of the humid subtropical. It is inhabited by fauna and flora of both climates, in winter, it regularly freezes over at Pittsburgh but rarely further south toward Cincinnati and Louisville. At Paducah, Kentucky, in the south, near the Ohios confluence with the Mississippi, Paducah was founded there because it is the northernmost ice-free reach of the Ohio. The Ohio River is formed by the confluence of the Allegheny and Monongahela rivers at Point State Park in Pittsburgh, from there, it flows northwest through Allegheny and Beaver counties, before making an abrupt turn to the south-southwest at the West Virginia–Ohio–Pennsylvania triple-state line. From there, it forms the border between West Virginia and Ohio, upstream of Wheeling, West Virginia, the river then follows a roughly southwest and then west-northwest course until Cincinnati, before bending to a west-southwest course for most of its length. The course forms the borders of West Virginia and Kentucky. The Ohio drains parts of 15 states in four regions, northeast New York, a small area of the southern border along the headwaters of the Allegheny. Pennsylvania, a corridor from the corner to north central border
17.
2001 Atlantic hurricane season
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The 2001 Atlantic hurricane season was a fairly active Atlantic hurricane season that produced 17 tropical cyclones,15 named storms, nine hurricanes, and four major hurricanes. The season officially lasted from June 1,2001, to November 30,2001, the season began with Tropical Storm Allison on June 4, and ended with Hurricane Olga, which dissipated on December 6. The most intense storm was Hurricane Michelle, which attained Category 4 strength on the Saffir–Simpson Hurricane Scale, three tropical cyclones made landfall on the United States, three directly affected Canada, and three directly affected Mexico and Central America. Overall, the season caused 105 fatalities, and $7.1 billion in damage, due to their severe damage, the names Allison, Iris, and Michelle were retired by the World Meteorological Organization. Klotzbachs team defined the average number of storms per season as 9.6 tropical storms,5.9 hurricanes,2.3 major hurricanes, on December 7,2000, Grays team issued its first extended-range forecast for the 2001 season, predicting above-average activity. It listed an 63 percent chance of at least one hurricane striking the U. S. mainland. The potential for major activity in the Caribbean was forecast to near average. On April 5,2001, a new forecast was issued, calling for 12 named storms,7 hurricanes, the estimated potential for at least one major hurricane to affect the U. S. On August 8,2001, NOAA revised its season estimate slightly upwards to nine to twelve named storms, of which 6 to 8 were to be hurricanes, the seasons activity was reflected with an accumulated cyclone energy rating of 110. ACE is only calculated for full advisories on tropical systems at or exceeding 34 knots or tropical storm strength, subtropical cyclones, including the latter portion of Allison and the initial portions of Karen, Noel, and Olga, are excluded from the total. Tropical Storm Allison developed from a wave in the northern Gulf of Mexico on June 4,2001. It drifted northward through the state, turned to the south, the storm continued towards the east-northeast, made landfall on Louisiana and then moved across the southeast United States and Mid-Atlantic. Allison was the first storm since Tropical Storm Frances in 1998 to affect the northern Texas coastline, the storm was a major flood disaster throughout its path from Texas to the Mid-Atlantic. The worst of the flooding occurred in Houston, Texas, where over 35 in of rain fell, the storm killed 41 people, of which 27 drowned. The storm also caused over $5 billion in damage, making it the costliest and second-deadliest tropical storm on record in the United States, Allison destroyed 2,744 homes, leaving 30,000 homeless with residential damages totaling to $1.76 billion. A tropical depression formed from a low level circulation on July 11 and it attained a maximum strength of 30 mph, with a pressure of 1,010 mbar, though vertical wind shear from a subtropical ridge to the north caused it to dissipate on July 12. On July 24, a tropical wave moved off the coast of Africa, the wave entered the Caribbean on July 29 and gained in organization and convection, and organized into Tropical Storm Barry on August 3. After fluctuations in intensity, the system attained winds of 70 mph in the Gulf of Mexico
18.
Synoptic scale meteorology
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The synoptic scale in meteorology is a horizontal length scale of the order of 1000 kilometres or more. This corresponds to a horizontal scale typical of mid-latitude depressions, most high and low-pressure areas seen on weather maps such as surface weather analyses are synoptic-scale systems, driven by the location of Rossby waves in their respective hemisphere. Low-pressure areas and their related frontal zones occur on the edge of a trough within the Rossby wave pattern. Most precipitation areas occur near frontal zones, the word synoptic is derived from the Greek word συνοπτικός, meaning seen together. The Navier–Stokes equations applied to atmospheric motion can be simplified by scale analysis in the synoptic scale and it can be shown that the main terms in horizontal equations are Coriolis force and pressure gradient terms, therefore, one can use geostrophic approximation. In vertical coordinates, the equation simplifies to the hydrostatic equilibrium equation. The first weather maps in the 19th century were drawn well after the fact to help devise a theory on storm systems, use of surface analyses began first in the United States, spreading worldwide during the 1870s. Use of the Norwegian cyclone model for frontal analysis began in the late 1910s across Europe, surface weather analyses have special symbols which show frontal systems, cloud cover, precipitation, or other important information. For example, an H represents high pressure, implying good, an L represents low pressure, which frequently accompanies precipitation. Various symbols are used not just for frontal zones and other surface boundaries on weather maps, areas of precipitation help determine the frontal type and location. Mesoscale systems and boundaries such as cyclones, outflow boundaries. Isobars are commonly used to place surface boundaries from the horse latitudes poleward, the descriptor extratropical refers to the fact that this type of cyclone generally occurs outside of the tropics, in the middle latitudes of the planet. These are the phenomena which along with anti-cyclones, drive the weather over much of the Earth. An extratropical cyclone can transform into a storm, and from there into a tropical cyclone, if it dwells over warm waters and develops central convection. High-pressure systems are associated with light winds at the surface and subsidence through the lower portion of the troposphere. Subsidence will generally dry out an air mass by adiabatic, or compressional, thus, high pressure typically brings clear skies. During the day, since no clouds are present to reflect sunlight, there is more incoming solar radiation. At night, the absence of means that outgoing longwave radiation is not absorbed
19.
Tropical wave
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All tropical waves form in the easterly flow along the equatorward side of the subtropical ridge or belt of high pressure which lies north and south of the Intertropical Convergence Zone. Tropical waves are carried westward by the prevailing easterly winds along the tropics and subtropics near the equator. They can lead to the formation of cyclones in the north Atlantic. Tropical wave study is aided by Hovmöller diagrams, a graph of meteorological data, a tropical wave normally follows an area of sinking, intensely dry air, blowing from the northeast. After the passage of the line, the wind veers southeast, the humidity abruptly rises. This yields widespread showers and thunderstorms, sometimes severe, as the wave moves westward, the showers gradually diminish. An exception to this rain is in the Atlantic, sometimes, a surge of dry air called the Saharan Air Layer follows a tropical wave, leaving cloudless skies, as convection is capped by the dry layer inversion. Also, any dust in the SAL reflects sunlight, cooling the air below it, Tropical waves in the Atlantic basin develop from disturbances which develop as far east as Sudan in east Africa and drift over the continent into the Atlantic ocean. These are generated or enhanced by the African Easterly Jet, approximately 60% of Atlantic tropical cyclones originate from tropical waves, while approximately 85% of intense Atlantic hurricanes develop from tropical waves. Tropical cyclones can sometimes degenerate back into a tropical wave and this normally occurs if upper-level wind shear is too strong. The storm can redevelop if the upper level shear abates, if a tropical wave is moving quickly, it can have strong winds of over tropical storm force, but is not considered a tropical storm unless it has a closed circulation. An example of this was Hurricane Claudette in 2003, where the wave had winds of 45 mph before developing a circulation. It has been suggested that some eastern Pacific Ocean tropical cyclones are formed out of tropical waves that originate in North Africa as well. A screaming eagle is a wave whose convective pattern loosely resembles the head of an eagle. This phenomenon is caused by shearing from either westerly winds aloft or strong winds at the surface. These systems are located within 25 degrees latitude of the equator. Rain showers and surface winds gusting to 29 mph are associated with these waves and they move across the ocean at a rate of 15 mph. Strong thunderstorm activity can be associated with the features when located east of an upper tropospheric trough
20.
Lesser Antilles
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The Lesser Antilles are a group of islands in the Caribbean Sea. Most form a long, partly volcanic island arc between the Greater Antilles to the north-west and the continent of South America, the islands form the eastern boundary of the Caribbean Sea with the Atlantic Ocean. Together, the Lesser Antilles and the Greater Antilles compose the Antilles, when combined with the Lucayan Archipelago, all three are known as the West Indies. The islands of the Lesser Antilles are divided into three groups, the Windward Islands in the south, the Leeward Islands in the north, and the Leeward Antilles in the west. The Windward Islands are so called because they were more windward to sailing ships arriving in the New World than the Leeward Islands, the trans-Atlantic currents and winds that provided the fastest route across the ocean brought these ships to the rough dividing line between the Windward and Leeward Islands. The Leeward Antilles consist of the Dutch ABC islands just off the coast of Venezuela, the Lesser Antilles more or less coincide with the outer edge of the Caribbean Plate. Many of the islands were formed as a result of the subduction of oceanic crust of the South American Plate under the Caribbean Plate in the Lesser Antilles subduction zone. This process is ongoing and is not only for many of the islands. The Lesser Antilles are divided into eight independent nations and numerous dependent, over one third of the total area and population of the Lesser Antilles lies within Trinidad and Tobago, a sovereign nation comprising the two southernmost islands of the Windward Island chain. Several islands along the north coast of Venezuela and politically part of country are also occasionally considered part of the Lesser Antilles. These are listed in the section below, the main Lesser Antilles are, Virgin Islands St. Thomas St. John St. They are the most southern islands of the Caribbean region, a Brief History of the Caribbean. New York, Facts on File,1992, the dictionary definition of Lesser Antilles at Wiktionary
21.
Caribbean Sea
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The Caribbean Sea is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. The entire area of the Caribbean Sea, the islands of the West Indies. The Caribbean Sea is one of the largest seas and has an area of about 2,754,000 km2, the seas deepest point is the Cayman Trough, between the Cayman Islands and Jamaica, at 7,686 m below sea level. The Caribbean coastline has many gulfs and bays, the Gulf of Gonâve, Gulf of Venezuela, Gulf of Darién, Golfo de los Mosquitos, Gulf of Paria, the Caribbean Sea has the worlds second biggest barrier reef, the Mesoamerican Barrier Reef. It runs 1,000 km along the coasts of Mexico, Belize, Guatemala, the name Caribbean derives from the Caribs, one of the regions dominant Native American groups at the time of European contact during the late 15th century. During the first century of development, Spanish dominance in the region remained undisputed, from the 16th century, Europeans visiting the Caribbean region identified the South Sea as opposed to the North Sea. The Caribbean Sea had been unknown to the populations of Eurasia until 1492, at that time the Western Hemisphere in general was unknown to Europeans. Following the discovery of the islands by Columbus, the area was colonised by several Western cultures. As of 2015 the area is home to 22 island territories, the International Hydrographic Organization defines the limits of the Caribbean Sea as follows, On the North. In the Windward Channel – a line joining Caleta Point and Pearl Point in Haïti, in the Mona Passage – a line joining Cape Engano and the extreme of Agujereada in Puerto Rico. From Galera Point through Trinidad to Galeota Point and thence to Baja Point in Venezuela, note that, although Barbados is an island on the same continental shelf, it is considered to be in the Atlantic Ocean rather than the Caribbean Sea. The Caribbean Sea is an oceanic sea largely situated on the Caribbean Plate, the Caribbean Sea is separated from the ocean by several island arcs of various ages. The youngest stretches from the Lesser Antilles to the Virgin Islands to the north east of Trinidad, the larger islands in the northern part of the sea Cuba, Hispaniola, Jamaica and Puerto Rico lie on an older island arc. The geological age of the Caribbean Sea is estimated to be between 160 and 180 million years and was formed by a fracture that split the supercontinent called Pangea in the Mesozoic Era. It is assumed the proto-caribbean basin existed in the Devonian period, in the early Carboniferous movement of Gondwana to the north and its convergence with the Euramerica basin decreased in size. The next stage of the Caribbean Seas formation began in the Triassic, powerful rifting led to the formation of narrow troughs, stretching from modern Newfoundland to the west coast of the Gulf of Mexico which formed siliciclastic sedimentary rocks. In the early Jurassic due to powerful marine transgression, water broke into the present area of the Gulf of Mexico creating a vast shallow pool, the emergence of deep basins in the Caribbean occurred during the Middle Jurassic rifting. The emergence of these marked the beginning of the Atlantic Ocean
22.
Low-pressure area
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A low-pressure area, low, or depression is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure systems form under areas of wind divergence that occur in the levels of the troposphere. The formation process of an area is known as cyclogenesis. Within the field of meteorology, atmospheric divergence aloft occurs in two areas, the first area is on the east side of upper troughs, which form half of a Rossby wave within the Westerlies. A second area of wind divergence aloft occurs ahead of embedded shortwave troughs, diverging winds aloft ahead of these troughs cause atmospheric lift within the troposphere below, which lowers surface pressures as upward motion partially counteracts the force of gravity. Thermal lows form due to localized heating caused by greater sunshine over deserts, since localized areas of warm air are less dense than their surroundings, this warmer air rises, which lowers atmospheric pressure near that portion of the Earths surface. Large-scale thermal lows over continents help drive monsoon circulations, low-pressure areas can also form due to organized thunderstorm activity over warm water. When this occurs over the tropics in concert with the Intertropical Convergence Zone, Monsoon troughs reach their northerly extent in August and their southerly extent in February. When a convective low acquires a well-hot circulation in the tropics it is termed a tropical cyclone, Tropical cyclones can form during any month of the year globally, but can occur in either the northern or southern hemisphere during November. Since clouds reflect sunlight, incoming solar radiation decreases, which causes lower temperatures during the day. At night the effect of clouds on outgoing longwave radiation, such as heat energy from the surface. The stronger the area of low pressure, the stronger the winds experienced in its vicinity, globally, low-pressure systems are most frequently located over the Tibetan Plateau and in the lee of the Rocky mountains. In Europe, recurring low-pressure weather systems are known as depressions. Cyclogenesis is the development and strengthening of cyclonic circulations, or low-pressure areas, cyclogenesis is the opposite of cyclolysis, and has an anticyclonic equivalent which deals with the formation of high-pressure areas—anticyclogenesis. Cyclogenesis is a term for several different processes, all of which result in the development of some sort of cyclone. Meteorologists use the term cyclone where circular pressure systems flow in the direction of the Earths rotation, the largest low-pressure systems are cold-core polar cyclones and extratropical cyclones which lie on the synoptic scale. Warm-core cyclones such as cyclones, mesocyclones, and polar lows lie within the smaller mesoscale. Subtropical cyclones are of intermediate size, cyclogenesis can occur at various scales, from the microscale to the synoptic scale
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Nicaragua
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Nicaragua, officially the Republic of Nicaragua, is the largest country in the Central American isthmus. Nicaraguas capital, Managua, is the countrys largest city and the third-largest city in Central America, the multi-ethnic population of six million includes indigenous peoples, Europeans, Africans, and Asians. Native tribes on the eastern coast speak their own languages, the Spanish Empire conquered the region in the 16th century. Nicaragua gained independence from Spain in 1821, since its independence, Nicaragua has undergone periods of political unrest, dictatorship, and fiscal crisis—the most notable causes that led to the Nicaraguan Revolution of the 1960s and 1970s. Nicaragua is a democratic republic. The biological diversity, warm climate and active volcanoes make Nicaragua an increasingly popular tourist destination. The name Nicaragua was coined by Spanish colonists based on the name Nicarao, when Spaniard Gil González Dávila came to Nicaragua in 1521 he found in the areas between Rivas and San Jorge the first pre-Columbian natives of Nicaragua. At the time the city was called Quauhcapolca and the cacique leaders name was Macuilmiquiztli. The Pipil migrated to Nicaragua from central Mexico after 500 BC, meanwhile, the Caribbean coast of Nicaragua was inhabited by other peoples, mostly Chibcha language groups. They had coalesced in Central America and migrated also to present-day northern Colombia and they lived a life based primarily on hunting and gathering. In 1502, Christopher Columbus became the first European known to have reached what is now Nicaragua as he sailed southeast toward the Isthmus of Panama, on his fourth voyage, Columbus explored the Miskito Coast on the Atlantic side of Nicaragua. The Spanish attempted to convert all three tribes to Christianity, Nicaragua and Nicarao and their people converted, but Dirangen, however, did not, the first attempt to conquer what is now known as Nicaragua was by Gil González Dávila, who arrived in Panama in January 1520. The first Spanish permanent settlements were founded in 1524, conquistador Francisco Hernández de Córdoba founded two of Nicaraguas principal towns in 1524, Granada on Lake Nicaragua was the first settlement, followed by León at a location west of Lake Managua. Córdoba soon built defenses for the cities and fought against incursions by other conquistadors, Córdoba was later publicly beheaded following a power struggle with Pedro Arias Dávila. His tomb and remains were discovered in 2000 in the ruins of León Viejo, the clashes among Spanish forces did not impede their destruction of the indigenous people and their culture. The series of battles came to be known as the War of the Captains, Pedro Arias Dávila was a winner, although he had lost control of Panama, he moved to Nicaragua and successfully established his base in León. Through adroit diplomatic machinations, he became the first governor of the colony, many indigenous people died as a result of new infectious diseases, compounded by neglect by the Spaniards, who controlled their subsistence. In 1610, the Momotombo volcano erupted, destroying the capital and it was rebuilt northwest of what is now known as the ruins of Old León
24.
Atmospheric convection
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Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability, mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes, there are a few general archetypes of atmospheric instability that correspond to convection and lack thereof. Steeper and/or positive lapse rates suggests atmospheric convection is more likely and this is because any displaced air parcels will become more buoyant, given their sign of adiabatic temperature change, in the steep lapse rate environments. Convection begins at the level of free convection, where it begins its ascent through the free convective layer, the rising parcel, if having enough momentum, will continue to rise to the maximum parcel level until negative buoyancy decelerates the parcel to a stop. Acceleration is of relevance to convection. Drag produced by the updraft creates a force to counter that from the buoyancy. This could be thought of as similar to the velocity of a falling object. This force from buoyancy can be measured by Convective Available Potential Energy, see the CAPE, buoyancy, and parcel links for a more in depth mathematical explanation of these processes. Within the atmosphere, this means from the surface to above the 500 hPa level, oceanic deep convection only occurs at a few locations. While less dynamically important than in the atmosphere, it is responsible for the spreading of cold water through the low layers of the ocean, as such, it is important for the large-scale temperature structure of the whole ocean. A thermal column is a section of rising air in the lower altitudes of the Earths atmosphere. Thermals are created by the heating of the Earths surface from solar radiation. The Sun warms the ground, which in turn warms the air directly above it, the warmer air expands, becoming less dense than the surrounding air mass, and creating a thermal low. The mass of air rises, and as it does. It stops rising when it has cooled to the temperature as the surrounding air. Associated with a thermal is a downward flow surrounding the thermal column, the downward moving exterior is caused by colder air being displaced at the top of the thermal
25.
National Hurricane Center
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The Technology and Science Branch provides technical support for the center, which includes new infusions of technology from abroad. Research to improve operational forecasts is done through the Hurricane Forecast Improvement Project, during the Atlantic and northeast Pacific hurricane seasons, the Hurricane Specialists Unit issues routine tropical weather outlooks for the northeast Pacific and northern Atlantic oceans. When tropical storm or hurricane conditions are expected within 48 hours, the first hurricane warning service was set up in the 1870s from Cuba with the work of Father Benito Viñes. C. in 1902. The central office in Washington, which evolved into the National Meteorological Center and Weather Prediction Center, Hurricane advisories issued every six hours by the regional hurricane offices began at this time. The Jacksonville hurricane warning office moved to Miami, Florida in 1943, Tropical cyclone naming began for Atlantic tropical cyclones using the Joint Army/Navy Phonetic Alphabet by 1947. In 1950, the Miami Hurricane Warning Office began to prepare the annual hurricane season summary articles, in the 1953 Atlantic season, the United States Weather Bureau began naming storms which reach tropical storm intensity with human names. The National Hurricane Research Project, begun in the 1950s, used aircraft to study tropical cyclones, on July 1,1956, a National Hurricane Information Center was established in Miami, Florida which became a warehouse for all hurricane-related information from one United States Weather Bureau office. The Miami Hurricane Warning Office moved from Lindsey Hopkins Hotel to the Aviation Building 4 miles to the northwest on July 1,1958, the Miami HWO moved to the campus of the University of Miami in 1964, and was referred to as the NHC in 1965. The Miami HWO tropical cyclone reports were regularly and took on their modern format in 1964. Beginning in 1973, the National Meteorological Center duties gained advisory responsibility for tracking and publicizing inland tropical depressions, the World Meteorological Organization assumed control of the Atlantic hurricane naming list in 1977. In 1978, the NHCs offices moved off the campus of the University of Miami across U. S. Highway 1 to the IRE Financial Building, male names were added into the hurricane list beginning in the 1979 season. The hurricane warning offices remained active past 1983, in 1984, the NHC was separated from the Miami Weather Service Forecast Office, which meant the meteorologist in charge at Miami was no longer in a position above the hurricane center director. By 1988, the NHC gained responsibility for eastern Pacific tropical cyclones as the former Eastern Pacific Hurricane Center in San Francisco was decommissioned, in 1992, Hurricane Andrew blew the WSR-57 weather radar and the anemometer off the roof of NHCs/the Miami State Weather Forecast offices. The radar was replaced with a WSR-88D NEXRAD system in April 1993 installed near Metro Zoo, in 1995, the NHC moved into a new hurricane-resistant facility on the campus of Florida International University, capable of withstanding 130 mph winds. Its name was changed to the Tropical Prediction Center in 1995, after the name change to TPC, the Hurricane Specialists were grouped as a separate NHC unit under the Tropical Prediction Center, separating themselves from the Tropical Analysis and Forecast Branch. On October 1,2010, the Tropical Prediction Center was renamed the NHC, the World Meteorological Organization continues to create and maintain the annual hurricane naming lists. Naming lists use a rotation, with the deadliest or most notable storm names retired from the rotation. The director of the National Hurricane Center is Richard Knabb, for the fiscal year of 2008, the budget for the NHC was $6.8 million
26.
Coordinated Universal Time
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Coordinated Universal Time, abbreviated to UTC, is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean time at 0° longitude. It is one of closely related successors to Greenwich Mean Time. For most purposes, UTC is considered interchangeable with GMT, the first Coordinated Universal Time was informally adopted on 1 January 1960. This change also adopted leap seconds to simplify future adjustments, a number of proposals have been made to replace UTC with a new system that would eliminate leap seconds, but no consensus has yet been reached. Leap seconds are inserted as necessary to keep UTC within 0.9 seconds of universal time, see the Current number of leap seconds section for the number of leap seconds inserted to date. The official abbreviation for Coordinated Universal Time is UTC and this abbreviation arose from a desire by the International Telecommunication Union and the International Astronomical Union to use the same abbreviation in all languages. English speakers originally proposed CUT, while French speakers proposed TUC, the compromise that emerged was UTC, which conforms to the pattern for the abbreviations of the variants of Universal Time. Time zones around the world are expressed using positive or negative offsets from UTC, the westernmost time zone uses UTC−12, being twelve hours behind UTC, the easternmost time zone, theoretically, uses UTC+12, being twelve hours ahead of UTC. In 1995, the nation of Kiribati moved those of its atolls in the Line Islands from UTC-10 to UTC+14 so that the country would all be on the same day. UTC is used in internet and World Wide Web standards. The Network Time Protocol, designed to synchronise the clocks of computers over the internet, computer servers, online services and other entities that rely on having a universally accepted time use UTC as it is more specific than GMT. If only limited precision is needed, clients can obtain the current UTC from a number of official internet UTC servers, for sub-microsecond precision, clients can obtain the time from satellite signals. UTC is also the standard used in aviation, e. g. for flight plans. Weather forecasts and maps all use UTC to avoid confusion about time zones, the International Space Station also uses UTC as a time standard. Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up by many time zones, UTC is also used in digital tachographs used on large goods vehicles under EU and AETR rules. UTC divides time into days, hours, minutes and seconds, days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 60 minutes, the number of seconds in a minute is usually 60, but with an occasional leap second, it may be 61 or 59 instead
27.
Cozumel
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Cozumel is an island in the Caribbean Sea off the eastern coast of Mexicos Yucatán Peninsula, opposite Playa del Carmen, and close to the Yucatán Channel. The economy of Cozumel is based on tourism, there are a number of visitors to the islands balnearios, scuba diving, and snorkeling. The main town on the island is San Miguel de Cozumel, the islands belongs to Cozumel Municipality of the state of Quintana Roo, Mexico. The name Cozumel was derived from the Mayan Cuzamil or Ah Cuzamil Peten in full, the island is located in the Caribbean Sea along the eastern side of the Yucatan Peninsula about 82 km south of Cancún and 19 km from the mainland. The island is about 48 km long and 16 km wide, with a total area of 477.961 km2, it is Mexicos largest Caribbean island, largest permanently inhabited island, and Mexicos third-largest island, following Tiburón Island and Isla Ángel de la Guarda. The majority of the population lives in the town of San Miguel. The municipality, which two small areas on the mainland enclaved within the Municipality of Solidaridad with a land area of 10.423 km2, has a total land area of 647.33 km2. The island is covered with mangrove forest which has many animal species. Cozumel is an island based on limestone, resulting in a karst topography. The highest natural point on the island is less than 15 m above sea level, the cenotes are deep water filled sinkholes formed by water percolating through the soft limestone soil during thousands of years. Cozumels cenotes are restricted to qualified cave divers with appropriate credentials, the dry season is short, from February to April, but even in these months precipitation is observed, averaging about 45 millimetres of rain per month. The wet season is lengthy, covering most of the months, with September and October being the wettest months, thunderstorms can occasionally occur during the wet season. Temperatures tend to remain stable with little variation from month to month though the temperatures are cooler from December to February with the coolest month averaging 22.9 °C, owing to its proximity to the sea, the island is fairly humid, with an average humidity of 83%. The wettest recorded month was October 1980 with 792 millimetres of precipitation, extremes range from 9.2 °C on January 18,1977 to 39.2 °C. The Maya are believed to have first settled Cozumel by the part of the 1st millennium AD. The island was sacred to Ix Chel, the Maya Moon Goddess, there are a number of ruins on the island, most from the Post-Classic period. The largest Maya ruins on the island were near the area and have now been destroyed. Today, the largest remaining ruins are at San Gervasio, located approximately at the center of the island, the first Spanish expedition to visit Cozumel was led by Juan de Grijalva in 1518
28.
Tropical cyclogenesis
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Tropical cyclogenesis is the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which mid-latitude cyclogenesis occurs, tropical cyclogenesis involves the development of a warm-core cyclone, due to significant convection in a favorable atmospheric environment. Tropical cyclones tend to develop during the summer, but have been noted in every month in most basins. Climate cycles such as ENSO and the Madden–Julian oscillation modulate the timing, there is a limit on tropical cyclone intensity which is strongly related to the water temperatures along its path. An average of 86 tropical cyclones of tropical storm intensity form annually worldwide, of those,47 reach hurricane/typhoon strength, and 20 become intense tropical cyclones. While these conditions are necessary for tropical cyclone formation, they do not guarantee that a tropical cyclone will form. Normally, a temperature of 26.5 °C spanning through at least a 50-metre depth is considered the minimum to maintain the special mesocyclone that is the tropical cyclone. These warm waters are needed to maintain the core that fuels tropical systems. This value is well above 16.1 °C, the average surface temperature of the oceans. Tropical cyclones are known to even when normal conditions are not met. In a moist atmosphere, this rate is 6.5 °C/km, while in an atmosphere with less than 100% relative humidity. Under a cold cyclone,500 hPa temperatures can fall as low as −30 °C and this also explains why moisture in the mid-levels of the troposphere, roughly at the 500 hPa level, is normally a requirement for development. However, when dry air is found at the same height, at heights near the tropopause, the 30-year average temperature was −77 °C. A recent example of a cyclone that maintained itself over cooler waters was Epsilon of the 2005 Atlantic hurricane season. Emanuels model is called the maximum intensity, or MPI. Maps created from this equation show regions where tropical storm and hurricane formation is possible and this does not take into account vertical wind shear. A minimum distance of 500 km from the equator is normally needed for tropical cyclogenesis, the Coriolis force imparts rotation on the flow and arises as winds begin to flow in toward the lower pressure created by the pre-existing disturbance. The existence of a significant Coriolis force allows the developing vortex to achieve gradient wind balance, even with perfect upper level conditions and the required atmospheric instability, the lack of a surface focus will prevent the development of organized convection and a surface low
29.
Prevailing winds
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Prevailing winds are winds that blow predominantly from a single general direction over a particular point on the Earths surface. The dominant winds are the trends in direction of wind with the highest speed over a point on the Earths surface. A regions prevailing and dominant winds acted by global patterns of movement in the Earths atmosphere, in general, easterly flow occurs at low and medium latitudes globally. In the mid-latitudes, westerly winds are the rule and their strength is determined by the polar cyclone. Highly elevated surfaces can induce a thermal low, which augments the environmental wind flow. Wind roses are used to determine the direction of the prevailing wind. Knowledge of the wind allows the development of prevention strategies for wind erosion of agricultural land. Sand dunes can orient themselves, or perpendicular to, the wind regime within coastal. Insects drift along with the wind, while birds are able to fly more independently of it. Prevailing winds in moun locations can lead to significant rainfall gradients within the topography, prevailing winds can have differences due to the uneven heating of the Earth. A wind rose is a tool used by meteorologists to give a succinct view of how wind speed. Presented in a coordinate grid, the wind rose shows the frequency of winds blowing from particular directions. The length of each spoke around the circle is related to the frequency that the blows from a particular direction per unit time. Each concentric circle represents a different frequency, emanating from zero at the center to increasing frequencies at the outer circles, a wind rose plot may contain additional information, in that each spoke is broken down into color-coded bands that show wind direction ranges. Wind roses typically use 8 or 16 cardinal directions, such as north, NNE, NE, the trade winds are the prevailing pattern of easterly surface winds found in the tropics near the Earths equator, equatorward of the subtropical ridge. These winds blow predominantly from the northeast in the Northern Hemisphere, the trade winds act as the steering flow for tropical cyclones that form over worlds oceans, guiding their path westward. Trade winds also steer African dust westward across the Atlantic Ocean into the Caribbean sea and these prevailing winds blow from the west to the east, and steer extra-tropical cyclones in this general manner. The winds are predominantly from the southwest in the Northern Hemisphere, the westerlies can be particularly strong, especially in the southern hemisphere, where there is less land in the middle latitudes to cause the flow pattern to amplify, which slows the winds down
30.
Rainband
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A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature, when noted on weather radar imagery, this precipitation elongation is referred to as banded structure. Rainbands within tropical cyclones are curved in orientation, tropical cyclone rainbands contain showers and thunderstorms that, together with the eyewall and the eye, constitute a hurricane or tropical storm. The extent of rainbands around a tropical cyclone can help determine the cyclones intensity, rainbands spawned near and ahead of cold fronts can be squall lines which are able to produce tornadoes. Rainbands associated with cold fronts can be warped by mountain barriers perpendicular to the fronts orientation due to the formation of a low-level barrier jet, bands of thunderstorms can form with sea breeze and land breeze boundaries, if enough moisture is present. If sea breeze rainbands become active enough just ahead of a cold front, banding within the comma head precipitation pattern of an extratropical cyclone can yield significant amounts of rain or snow. Behind extratropical cyclones, rainbands can form downwind of relative warm bodies of such as the Great Lakes. If the atmosphere is cold enough, these rainbands can yield heavy snow, rainbands in advance of warm occluded fronts and warm fronts are associated with weak upward motion, and tend to be wide and stratiform in nature. Wider rain bands can occur behind cold fronts, which tend to have more stratiform and these bands in the comma head are associated with areas of frontogensis, or zones of strengthening temperature contrast. Southwest of extratropical cyclones, curved flow bringing cold air across the relatively warm Great Lakes can lead to narrow lake effect snow bands which bring significant localized snowfall, rainbands exist in the periphery of tropical cyclones, which point towards the cyclones center of low pressure. Rainbands within tropical cyclones require ample moisture and a low level pool of cooler air, bands located 80 kilometres to 150 kilometres from a cyclones center migrate outward. They are capable of producing heavy rains and squalls of wind, as well as tornadoes, some rainbands move closer to the center, forming a secondary, or outer, eyewall within intense hurricanes. Within this method, the extent of banding and difference in temperature between the eye and eyewall is used to assign a maximum sustained wind and a central pressure. Central pressure values for their centers of low pressure derived from this technique are approximate, different programs have been studying these rainbands, including RAINEX. Convective rainbands can form parallel to terrain on its windward side and their spacing is normally 5 kilometres to 10 kilometres apart. If enough moisture is present, sea breeze and land breeze fronts can form convective rainbands, sea breeze front thunderstorm lines can become strong enough to mask the location of an approaching cold front by evening. The edge of ocean currents can lead to the development of bands due to heat differential at this interface. Downwind of islands, bands of showers and thunderstorms can develop due to low level wind convergence downwind of the island edges, offshore California, this has been noted in the wake of cold fronts
31.
Tropical cyclone naming
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Tropical cyclones and subtropical cyclones are named by various warning centers to provide ease of communication between forecasters and the general public regarding forecasts, watches, and warnings. The names are intended to reduce confusion in the event of concurrent storms in the same basin, generally once storms produce sustained wind speeds of more than 33 knots, names are assigned in order from predetermined lists depending on which basin they originate. Before the formal start of naming, tropical cyclones were named after places, objects, the credit for the first usage of personal names for weather systems is generally given to the Queensland Government Meteorologist Clement Wragge, who named systems between 1887 and 1907. This system of naming weather systems subsequently fell into disuse for years after Wragge retired. Before the formal start of naming, tropical cyclones were named after places, objects. The credit for the first usage of names for weather systems is generally given to the Queensland Government Meteorologist Clement Wragge. This system of naming weather systems subsequently fell into disuse for years after Wragge retired until it was revived in the latter part of World War II for the Western Pacific. Formal naming schemes have subsequently introduced for the North Atlantic, Eastern, Central, Western and Southern Pacific basins as well as the Australian region. This is especially important when multiple storms are occurring simultaneously in the ocean basin. Names are generally assigned in order from predetermined lists, once they produce one, however, standards vary from basin to basin, with some systems named in the Western Pacific when they develop into tropical depressions or enter PAGASAs area of responsibility. Within the Southern Hemisphere, systems must be characterized by a significant amount of gale-force winds occurring around the center before they are named, PAGASA also retires the names of significant tropical cyclones when they have caused at least ₱1 billion in damage and/or have caused at least 300 deaths. There are six lists of names which rotate every six years and begin with the first letters A—W used, skipping Q and U, the names of significant tropical cyclones are retired from the lists, with a replacement name selected at the next World Meteorological Organizations Hurricane Committee meeting. If all of the names on a list are used, storms are named after the letters of the Greek alphabet, significant tropical cyclones have their names retired from the lists and a replacement name selected at the next World Meteorological Organization Hurricane Committee. When a tropical depression intensifies into a storm to the north of the Equator between the coastline of the Americas and 140°W, it will be named by the NHC. There are six lists of names which rotate every six years and begin with the letters A—Z used, skipping Q and U, the names of significant tropical cyclones are retired from the lists, with a replacement name selected at the next World Meteorological Organizations Hurricane Committee. If all of the names on a list are used, storms are named using the letters of the Greek alphabet, when a tropical depression intensifies into a tropical storm to the north of the Equator between 140°W and 180°, it is named by the CPHC. Significant tropical cyclones have their names retired from the lists, with a replacement name selected at the next Hurricane Committee meeting, Tropical cyclones that occur within the Northern Hemisphere between the anti-meridian and 100°E are officially named by the Japan Meteorological Agency when they become tropical storms. However, PAGASA also names tropical cyclones that occur or develop into tropical depressions within their area of responsibility between 5°N–25°N and 115°E-135°E
32.
Gulf of Mexico
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The Gulf of Mexico is an ocean basin largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. The U. S. states of Alabama, Florida, Louisiana, Mississippi and Texas border the Gulf on the north, Atlantic and Pacific coasts, or sometimes the south coast, in juxtaposition to the Great Lakes region being the north coast. One of the seven main areas is the Gulf of Mexico basin. The Gulf of Mexico formed approximately 300 million years ago as a result of plate tectonics, the Gulfs basin is roughly oval and is approximately 810 nautical miles wide and floored by sedimentary rocks and recent sediments. It is connected to part of the Atlantic Ocean through the Florida Straits between the U. S. and Cuba, and with the Caribbean Sea via the Yucatan Channel between Mexico and Cuba, with the narrow connection to the Atlantic, the Gulf experiences very small tidal ranges. The size of the Gulf basin is approximately 1.6 million km2, almost half of the basin is shallow continental shelf waters. The basin contains a volume of roughly 2,500 quadrillion liters, the consensus among geologists who have studied the geology of the Gulf of Mexico, is that prior to the Late Triassic, the Gulf of Mexico did not exist. It was created by the collision of plates that formed Pangea. As interpreted by Roy Van Arsdale and Randel T. Cox, geologists and other Earth scientists agree in general that the present Gulf of Mexico basin originated in Late Triassic time as the result of rifting within Pangea. The rifting was associated with zones of weakness within Pangea, including sutures where the Laurentia, South American, first, there was a Late Triassic-Early Jurassic phase of rifting during which rift valleys formed and filled with continental red beds. Second, as rifting progressed through Early and Middle Jurassic time and it was at this time that tectonics first created a connection to the Pacific Ocean across central Mexico and later eastward to the Atlantic Ocean. This flooded the basin created by rifting and crustal thinning to create the Gulf of Mexico. While the Gulf of Mexico was a basin, the subsiding transitional crust was blanketed by the widespread deposition of Louann Salt. Initially, during the Late Jurassic, continued rifting widened the Gulf of Mexico and progressed to the point that sea-floor spreading, at this point, sufficient circulation with the Atlantic Ocean was established that the deposition of Louann Salt ceased. During the Late Jurassic through Early Cretaceous, the occupied by the Gulf of Mexico experienced a period of cooling. The subsidence was the result of a combination of stretching, cooling. Initially, the combination of stretching and cooling caused about 5–7 km of tectonic subsidence of the central thin transitional
33.
Bay of Campeche
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The Bay of Campeche, or Campeche Sound, is a bight in the southern area of the Gulf of Mexico. It is surrounded on three sides by the Mexican states of Campeche, Tabasco and Veracruz, the area of the bay is 6,000 square miles and maximum depth of the bay is approximately 180 feet. It was named by Francisco Hernández de Córdoba and Antón de Alaminos during their expedition in 1517, the Cantarell Complex of five oil fields lies beneath the Bay of Campeche. In 2003 it was the second most productive oil field in the world, during the months of June and July, the Bay of Campeche is considered one of the hot breeding spots for Atlantic hurricanes. The bay is considered the eastern border on the main migration routes for birds in the Americas. Where do hurricanes form and where do they strike, archived from the original on 2005-11-20. Archived from the original on 17 April 2006
34.
Eye (cyclone)
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The eye is a region of mostly calm weather at the center of strong tropical cyclones. The eye of a storm is a circular area, typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weather occurs, the cyclones lowest barometric pressure occurs in the eye and can be as much as 15 percent lower than the pressure outside the storm. In strong tropical cyclones, the eye is characterized by light winds and clear skies, surrounded on all sides by a towering, symmetric eyewall. In weaker tropical cyclones, the eye is well defined and can be covered by the central dense overcast. Weaker or disorganized storms may also feature an eyewall that does not completely encircle the eye or have an eye that features heavy rain. In all storms, however, the eye is the location of the minimum barometric pressure - where the atmospheric pressure at sea level is the lowest. A typical tropical cyclone will have an eye of approximately 30–65 km across, the eye may be clear or have spotty low clouds, it may be filled with low- and mid-level clouds, or it may be obscured by the central dense overcast. There is, however, very little wind and rain, especially near the center and this is in stark contrast to conditions in the eyewall, which contains the storms strongest winds. Due to the mechanics of a cyclone, the eye. While normally quite symmetric, eyes can be oblong and irregular, a large ragged eye is a non-circular eye which appears fragmented, and is an indicator of a weak or weakening tropical cyclone. An open eye is an eye which can be circular, but the eyewall does not completely encircle the eye, also indicating a weakening, both of these observations are used to estimate the intensity of tropical cyclones via Dvorak analysis. Eyewalls are typically circular, however, distinctly polygonal shapes ranging from triangles to hexagons occasionally occur. While typical mature storms have eyes that are a few miles across, rapidly intensifying storms can develop an extremely small, clear. Storms with pinhole eyes are prone to fluctuations in intensity. Small/minuscule eyes—those less than 10 nmi across—often trigger eyewall replacement cycles and this can take place anywhere from fifteen to hundreds of kilometers outside the inner eye. The storm then develops two concentric eyewalls, or an eye within an eye, in most cases, the outer eyewall begins to contract soon after its formation, which chokes off the inner eye and leaves a much larger but more stable eye. While the replacement cycle tends to weaken storms as it occurs and this may trigger another re-strengthen cycle of eyewall replacement
35.
Trough (meteorology)
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A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts. Unlike fronts, there is not a symbol for a trough on a weather chart. The weather charts in countries or regions mark troughs by a line. In the United States, a trough may be marked as a dashed line. In the UK, Hong Kong and Fiji, it is represented by a line extended from a low pressure center or between two low pressure centers, in Macau and Australia, it is a dashed line. If they are not marked, troughs may still be identified as an extension of isobars away from a low pressure center, sometimes the region between two high pressure centers may assume the character of a trough when there is a detectable wind shift noted at the surface. In the absence of a shift, the region is designated a col. If a trough forms in the mid-latitudes, a difference between two sides of the trough usually exists in the form of a weather front. A weather front is less convective than a trough in the tropics or subtropics. Sometimes collapsed frontal systems will degenerate into troughs, convective cells may develop in the vicinity of troughs and give birth to a tropical cyclone. Some tropical or subtropical regions such as the Philippines or south China are greatly affected by convection cells along a trough, in the mid-latitude westerlies, troughs and ridges often alternate, especially when upper-level winds are in a high-amplitude pattern. Tropical waves are a type of trough in easterly currents, a cyclonic northward deflection of the trade winds, troughs may be at the surface, or aloft, or both under various conditions. Most troughs bring clouds, showers, and a wind shift and this results from convergence or squeezing which forces lifting of moist air behind the trough line. In addition to standard troughs, some may be described further with a term indicating a specific or a set of characteristics. An inverted trough is a trough which is oriented opposite to most troughs of the mid-latitudes. Most inverted troughs are tropical waves, the situation is opposite in the Southern Hemisphere. Inverted troughs in both hemispheres move to the west from the east, while mid-latitude troughs generally move with the westerlies toward the east
36.
Sea surface temperature
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Sea surface temperature is the water temperature close to the oceans surface. The exact meaning of surface varies according to the measurement method used, air masses in the Earths atmosphere are highly modified by sea surface temperatures within a short distance of the shore. Localized areas of snow can form in bands downwind of warm water bodies within an otherwise cold air mass. Warm sea surface temperatures are known to be a cause of tropical cyclogenesis over the Earths oceans, tropical cyclones can also cause a cool wake, due to turbulent mixing of the upper 30 metres of the ocean. SST changes diurnally, like the air above it, but to a lesser degree, there is less SST variation on breezy days than on calm days. Coastal SSTs can cause winds to generate upwelling, which can significantly cool or warm nearby landmasses. Onshore winds can cause a considerable warm-up even in areas where upwelling is fairly constant and its values are important within numerical weather prediction as the SST influences the atmosphere above, such as in the formation of sea breezes and sea fog. It is also used to calibrate measurements from weather satellites, there are a variety of techniques for measuring this parameter that can potentially yield different results because different things are actually being measured. Away from the sea surface, general temperature measurements are accompanied by a reference to the specific depth of measurement. Sea surface temperature measurements are confined to the top portion of the ocean, SST was one of the first oceanographic variables to be measured. Benjamin Franklin suspended a mercury thermometer from a ship travelling between the United States and Europe in his survey of the Gulf stream in the late eighteenth century. SST was later measured by dipping a thermometer into a bucket of water that was drawn from the sea surface. The first automated technique for determining SST was accomplished by measuring the temperature of water in the port of large ships. These observations have a bias of around 0.6 °C due to the heat of the engine room. This bias has led to changes in the perception of global warming since 2000, fixed weather buoys measure the water temperature at a depth of 3 metres. Measurements of SST have had inconsistencies over the last 130 years due to the way they were taken, in the nineteenth century, measurements were taken in a bucket off of a ship. However, there was a variation in temperature because of the differences in buckets. Samples were collected in either a wood or a canvas bucket
37.
High-pressure area
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A high-pressure area, high or anticyclone is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward from the higher areas near their centers towards the lower pressure areas further from their centers. Viewed from above this twist in wind direction is in the direction as the rotation of the planet. The strongest high-pressure areas are associated with air masses which push away out of polar regions during the winter when there is less sun to warm neighboring regions. These Highs change character and weaken once they move further over relatively warmer water bodies, many of the features of Highs may be understood in context of middle- or meso-scale and relatively enduring dynamics of a planets atmospheric circulation. For example, massive atmospheric subsidences occur as part of the branches of Ferrel cells. Hadley cells help form the ridge, steer tropical waves. The subtropical ridge also helps form most of the worlds deserts, on English-language weather maps, high-pressure centers are identified by the letter H. Weather maps in other languages may use different letters or symbols. The direction of flow around an atmospheric high-pressure area and a low-pressure area, as seen from above. High-pressure systems rotate clockwise in the northern Hemisphere, low-pressure systems rotate counterclockwise in the southern hemisphere, the scientific terms in English used to describe the weather systems generated by highs and lows were introduced in the mid-1800s, mostly by the British. The scientific theories which explain the general phenomena originated about two centuries earlier, the term Cyclone was coined by Henry Piddington of the British East India Company to describe the devastating storm of December 1789 in Coringa, India. A cyclone forms around a low-pressure area, anticyclone, the term for the kind of weather around a high-pressure area, was coined in 1877 by Francis Galton to indicate an area whose winds revolved in the opposite direction of a cyclone. In British English, the direction of clockwise is referred to as anticlockwise. So, both the earth and winds around a low-pressure area rotate counter-clockwise in the hemisphere. The opposite to two cases occurs in the case of a high. These results derive from the Coriolis effect, that explains in detail the physics. High-pressure systems form due to motion through the troposphere, the atmospheric layer where weather occurs. Preferred areas within a flow pattern in higher levels of the troposphere are beneath the western side of troughs
38.
Rapid intensification
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Depending on its location and strength, a tropical cyclone is referred to by names such as hurricane, typhoon /taɪˈfuːn/, tropical storm, cyclonic storm, tropical depression, and simply cyclone. A hurricane is a storm that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean, Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through the evaporation of water from the ocean surface and this energy source differs from that of mid-latitude cyclonic storms, such as noreasters and European windstorms, which are fueled primarily by horizontal temperature contrasts. The strong rotating winds of a tropical cyclone are a result of the conservation of momentum imparted by the Earths rotation as air flows inwards toward the axis of rotation. As a result, they form within 5° of the equator. Tropical cyclones are typically between 100 and 2,000 km in diameter, Tropical refers to the geographical origin of these systems, which form almost exclusively over tropical seas. Cyclone refers to their nature, with wind blowing counterclockwise in the Northern Hemisphere. The opposite direction of circulation is due to the Coriolis effect, in addition to strong winds and rain, tropical cyclones are capable of generating high waves, damaging storm surge, and tornadoes. They typically weaken rapidly over land where they are cut off from their energy source. For this reason, coastal regions are vulnerable to damage from a tropical cyclone as compared to inland regions. Heavy rains, however, can cause significant flooding inland, though their effects on human populations are often devastating, tropical cyclones can relieve drought conditions. They also carry heat away from the tropics and transport it toward temperate latitudes. Tropical cyclones are areas of low pressure in the troposphere. On Earth, the pressures recorded at the centers of tropical cyclones are among the lowest ever observed at sea level, the environment near the center of tropical cyclones is warmer than the surroundings at all altitudes, thus they are characterized as warm core systems. The near-surface wind field of a cyclone is characterized by air rotating rapidly around a center of circulation while also flowing radially inwards. At the outer edge of the storm, air may be nearly calm, however, due to the Earths rotation, as air flows radially inward, it begins to rotate cyclonically in order to conserve angular momentum. At an inner radius, air begins to ascend to the top of the troposphere and this radius is typically coincident with the inner radius of the eyewall, and has the strongest near-surface winds of the storm, consequently, it is known as the radius of maximum winds. Once aloft, air flows away from the center, producing a shield of cirrus clouds
39.
Maximum sustained wind
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The maximum sustained wind associated with a tropical cyclone is a common indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a distance defined as the radius of maximum wind, unlike gusts, the value of these winds are determined via their sampling and averaging the sampled results over a period of time. Surface winds are variable due to friction between the atmosphere and the Earths surface, as well as near hills and mountains over land. Over the ocean, satellite imagery determines the value of the sustained winds within a tropical cyclone. Land, ship, aircraft reconnaissance observations, and radar imagery can also estimate this quantity and this value helps determine damage expected from a tropical cyclone, through use of such scales as the Saffir-Simpson scale. However, the United States National Weather Service defines sustained winds within tropical cyclones by averaging winds over a period of one minute, measured at the same 10 metres height. This is an important distinction, as the value of the highest one-minute sustained wind is about 14% greater than a sustained wind over the same period. In most tropical cyclone basins, use of the satellite-based Dvorak technique is the method used to determine a tropical cyclones maximum sustained winds. The extent of banding and difference in temperature between the eye and eyewall is used within the technique to assign a maximum sustained wind. Central pressure values for their centers of low pressure are approximate, the intensity of example hurricanes is derived from both the time of landfall and the maximum intensity. The tracking of individual clouds on minutely satellite imagery could be used in the future in estimating surface winds speeds for tropical cyclones, ship and land observations are also used, when available. Doppler weather radar can be used in the manner to determine surface winds with tropical cyclones near land. Friction between the atmosphere and the Earths surface causes a 20% reduction in the wind at the surface of the Earth, surface roughness also leads to significant variation of wind speeds. Over land, winds maximize at hill or mountain crests, while sheltering leads to wind speeds in valleys. Compared to over water, maximum sustained winds over land average 8% lower, in most basins, maximum sustained winds are used to define their category. In the Atlantic and northeast Pacific oceans, the Saffir-Simpson scale is used and this scale can be used to determine possible storm surge and damage impact on land. In most basins, the category of the cyclone is determined from the cyclones maximum sustained wind. Only in Australia is this quantity not used to define the tropical category, in their basin
40.
Atmospheric pressure
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Atmospheric pressure, sometimes also called barometric pressure, is the pressure exerted by the weight of air in the atmosphere of Earth. In most circumstances atmospheric pressure is approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. On average, a column of air one square centimetre in cross-section, measured from sea level to the top of the atmosphere, has a mass of about 1.03 kilograms and that force is a pressure of 10.1 N/cm2 or 101 kN/m2. A column 1 square inch in cross-section would have a weight of about 14.7 lb or about 65.4 N and it is modified by the planetary rotation and local effects such as wind velocity, density variations due to temperature and variations in composition. The standard atmosphere is a unit of pressure defined as 101325 Pa, the mean sea level pressure is the average atmospheric pressure at sea level. This is the pressure normally given in weather reports on radio, television. When barometers in the home are set to match the weather reports, they measure pressure adjusted to sea level. The altimeter setting in aviation, is an atmospheric pressure adjustment, average sea-level pressure is 1013.25 mbar. In aviation weather reports, QNH is transmitted around the world in millibars or hectopascals, except in the United States, Canada, however, in Canadas public weather reports, sea level pressure is instead reported in kilopascals. The highest sea-level pressure on Earth occurs in Siberia, where the Siberian High often attains a sea-level pressure above 1050 mbar, the lowest measurable sea-level pressure is found at the centers of tropical cyclones and tornadoes, with a record low of 870 mbar. Pressure varies smoothly from the Earths surface to the top of the mesosphere, although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round. As altitude increases, atmospheric pressure decreases, one can calculate the atmospheric pressure at a given altitude. Temperature and humidity affect the atmospheric pressure, and it is necessary to know these to compute an accurate figure. The graph at right was developed for a temperature of 15 °C, at low altitudes above the sea level, the pressure decreases by about 1.2 kPa for every 100 meters. See pressure system for the effects of air pressure variations on weather, Atmospheric pressure shows a diurnal or semidiurnal cycle caused by global atmospheric tides. This effect is strongest in tropical zones, with an amplitude of a few millibars and these variations have two superimposed cycles, a circadian cycle and semi-circadian cycle. The highest adjusted-to-sea level barometric pressure recorded on Earth was 1085.7 hPa measured in Tosontsengel
41.
Eyewall replacement cycle
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Eyewall replacement cycles, also called concentric eyewall cycles, naturally occur in intense tropical cyclones, generally with winds greater than 185 km/h, or major hurricanes. Since the strongest winds are in a cyclones eyewall, the tropical cyclone usually weakens during this phase, eventually the outer eyewall replaces the inner one completely, and the storm may re-intensify. The discovery of this process was responsible for the end of the U. S. governments hurricane modification experiment Project Stormfury. This project set out to seed clouds outside the eyewall, apparently causing a new eyewall to form, when it was discovered that this was a natural process due to hurricane dynamics, the project was quickly abandoned. Almost every intense hurricane undergoes at least one of these cycles during its existence, recent studies have shown that nearly half of all tropical cyclones, and nearly all cyclones with sustained winds over 204 kilometres per hour, undergo eyewall replacement cycles. Hurricane Allen in 1980 went through repeated eyewall replacement cycles, fluctuating between Category 5 and Category 3 status on the Saffir-Simpson Hurricane Scale several times, Hurricane Juliette was a rare documented case of triple eyewalls. Typhoon June was the first reported case of triple eyewalls, the first tropical system to be observed with concentric eyewalls was Typhoon Sarah by Fortner in 1956, which he described as an eye within an eye. The storm was observed by an aircraft to have an inner eyewall at 6 kilometres. During a subsequent flight 8 hours later, the eyewall had disappeared, the outer eyewall had reduced to 16 kilometres. The next hurricane observed to have concentric eyewalls was Hurricane Donna in 1960, radar from reconnaissance aircraft showed an inner eye that varied from 10 miles at low altitude to 13 miles near the tropopause. In between the two eyewalls was an area of clear skies that extended vertically from 3,000 feet to 25,000 feet, the low-level clouds at around 3,000 feet were described as stratocumulus with concentric horizontal rolls. The inner eyewall was reported to heights near 45,000 feet while the inner eyewall only extended to 30,000 feet. 12 hours after identifying a concentric eyewalls, the eyewall had dissipated. Hurricane Beulah in 1967 was the first tropical cyclone to have its eyewall replacement cycle observed from beginning to end, previous observations of concentric eyewalls were from aircraft-based platforms. Beulah was observed from the Puerto Rico land-based radar for 34 hours during which time a double eyewall formed and dissipated and it was noted that Beulah reached maximum intensity immediately prior to undergoing the eyewall replacement cycle, and that it was probably more than a coincidence. Previous eyewall replacement cycles had been observed to decrease the intensity of the storm, the increased rate of precipitation would result in dissipation of the storm. By early 1960, the theory was that the eyewall of a hurricane was inertially unstable. Therefore, seeding the storm outside the eyewall would release more latent heat, the expansion of the eyewall would be accompanied with a decrease in the maximum wind speed through conservation of angular momentum
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Pensacola Beach, Florida
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Pensacola Beach is an unincorporated community located on Santa Rosa Island, a barrier island, in Escambia County, Florida, United States. It is situated south of Pensacola in the Gulf of Mexico, as of the 2000 census, the community had a total population of 2,738. Pensacola Beach is part of the Pensacola–Ferry Pass–Brent Metropolitan Statistical Area, also see, History of Pensacola, Florida. Francisco Maldonado, a lieutenant under Conquistador Hernando de Soto, visited the area during the early Spanish exploration of North America and he anchored in Pensacola Bay for the winter of 1539–1540. In 1559, Don Tristan de Luna y Arellano led the first settlement of the region and his 11 ships, with 1500 settlers, anchored in the bay and established its colony on the site of todays Naval Air Station Pensacola. A hurricane decimated the colony a few later, killing hundreds. Suffering long-term famine and fighting, this first settlement was abandoned in 1561. A presidio was constructed on Santa Rosa Island in 1722 near the location of the more recent Fort Pickens, hurricanes in 1741 and 1752 forced its relocation to the mainland. Pensacola Beach for many years remained largely undeveloped, with a bar, tennis courts, bath houses, and a restaurant, it was a popular resort until it eventually closed in the 1960s. The entire island was owned by the federal government. As a result, all structures on the island have 99-year renewable leases with the SRIA rather than ownership of the land itself, Pensacola Beach is located at 30°20′00″N 87°08′15″W, on the barrier island of Santa Rosa. It is bordered to the south by the Gulf of Mexico, to the north by Santa Rosa Sound and Pensacola Bay, Pensacola Beach is home to some of the tallest buildings between Mobile and Tallahassee. The list below ranks the buildings in height, while generally cooler than most of peninsular Florida, Pensacola Beach maintains a more stable temperature year round than inland areas of Pensacola and Escambia County. As such, winter lows are several degrees warmer than Pensacola proper and summer highs are generally cooler as a result of the surrounding waters, as with many islands, Pensacola Beach enjoys sea breezes which begin around noon and end around sunset in the summer. Oil from the explosion did not reach Pensacola Beaches until June 4,2010, crews posted along Escambia County’s coastline quickly cleaned much of the oil that was evident along the beaches. Tourism in the Pensacola Beach area was affected during the summer of 2010. As a community located on a barrier island, Pensacola Beach is vulnerable to hurricanes. Landfalling storms have been known to drive storm surge over the island, damaging or destroying man made structures, in 1995, two hurricanes made landfall on the island
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Navarre, Florida
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Navarre is an unincorporated community in Santa Rosa County in the northwest Florida Panhandle. It is a community for mostly U. S. Military personnel, Federal Civil Servants, local population, retirees, Navarre is about 25 miles east of Pensacola and about 15 miles west of Fort Walton Beach. The community is centered on the junction of U. S. Route 98. Residents and visitors alike enjoy riding or jogging on the several scenic bike paths, in 1693, Spanish explorers Carlos de Sigüenza y Góngora and Admiral Andrés de Pez y Malzarraga, set sail from Veracruz, Mexico. A skilled cartographer, scientist, mathematician and theologian, Sigüenza was responsible for scouting and mapping possible sites of Spanish colonization in Northwest Florida during the expedition. While traveling in the area of East Bay in April 1693, on April 11,1693, while sailing up East Bay River, sailors aboard the Spanish ships noticed a group of Native Americans observing them from a camp near the shore. In order to greet the natives, a party was sent out. By the time the Spanish reached the shore however, the Native Americans were gone, at the natives quickly abandoned camp, the Spanish discovered half-cooked pieces of buffalo meat sitting over a fire, along with a fierce dog guarding the site. Due to the number of oak trees in that place. After erecting a cross and leaving gifts for the natives. Upon later return to El Robledal, the explorers noticed that their gifts had been taken, in return, the natives had also constructed a wooden cross and left a buffalo hide as a peace offering. The earliest-known map of Robledal dates from 1693, the year as the Pez-Sigüenza Expedition. Three years later, in a 1698 map by Don Andrés de Arriola y Guzmán, approximately 41 years before Guy H. Wyman platted Navarre, a small settlement named Eagan arose in 1884. The settlement, composed of 40 families, was located off the Santa Rosa Sound, the settlement, which formerly existed as a post office location, was named after its first postmaster, John Eagan Esq. A famous Pensacola lawyer and politician, following the post office’s discontinuation on September 11,1884, families continued to live in the area, and the town continued to appear on area maps even into the 1890s. The land upon which Eagan existed would, in fact, later become what is now known as Navarre, the founder of Navarre was Guy Wyman, a colonel in the United States Army. During World War I, he met a French nurse named Noelle, at the time, immigration policies would not allow him to bring her to the United States as a fiancée or even as a wife, but he could bring her back as his legal child
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Lake Ontario
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Lake Ontario is one of the five Great Lakes of North America. Ontario, Canadas most populous province, was named for the lake, in the Wyandot language, ontarío means “Lake of Shining Waters”. Its primary inlet is the Niagara River from Lake Erie, the last in the Great Lakes chain, Lake Ontario serves as the outlet to the Atlantic Ocean via the St. Lawrence River. Lake Ontario is the easternmost of the Great Lakes and the smallest in surface area and it is the 14th largest lake in the world. When its islands are included, the lake has a shoreline that is 712 miles long. As the last lake in the Great Lakes hydrologic chain, Lake Ontario has the lowest mean elevation of the lakes at 243 feet above sea level,326 feet lower than its neighbor upstream. Its maximum length is 193 statute miles and its width is 53 statute miles. The lakes average depth is 47 fathoms 1 foot, with a depth of 133 fathoms 4 feet. The lakes primary source is the Niagara River, draining Lake Erie, the drainage basin covers 24,720 square miles. As with all the Great Lakes, water levels both within the year and among years. These water level fluctuations are a part of lake ecology. The lake also has an important freshwater fishery, although it has negatively affected by factors including over-fishing, water pollution. Baymouth bars built by prevailing winds and currents have created a significant number of lagoons and sheltered harbors, mostly near Prince Edward County, Ontario, perhaps the best-known example is Toronto Bay, chosen as the site of the Upper Canada capital for its strategic harbour. Other prominent examples include Hamilton Harbour, Irondequoit Bay, Presquile Bay, the bars themselves are the sites of long beaches, such as Sandbanks Provincial Park and Sandy Island Beach State Park. These sand bars are associated with large wetlands, which support large numbers of plant and animal species. Presquile, on the shore of Lake Ontario, is particularly significant in this regard. The lake basin was carved out of soft, weak Silurian-age rocks by the Wisconsin ice sheet during the last ice age, the action of the ice occurred along the pre-glacial Ontarian River valley which had approximately the same orientation as todays basin. As the ice sheet retreated toward the north, it still dammed the St. Lawrence valley outlet and this stage is known as Lake Iroquois
