1.
Southern California
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Southern California, often abbreviated as SoCal, is a geographic and cultural region that generally comprises Californias 10 southernmost counties. The region is described as eight counties, based on demographics and economic ties, Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara. The more extensive 10-county definition, which includes Kern and San Luis Obispo counties, is used and is based on historical political divisions. Southern California is an economic center for the state of California. The 8-county and 10-county definitions are not used for the greater Southern California Megaregion, the megaregions area is more expansive, extending east into Las Vegas, Nevada and south across the Mexican border into Tijuana.5 million people. With over 22 million people, Southern California contains roughly 60 percent of Californias population, located east of Southern California is the Colorado Desert and the Colorado River at the border with Arizona. The Mojave Desert is located at the border with the state of Nevada while towards the south is the Mexico–United States border, within Southern California are two major cities, Los Angeles and San Diego, as well as three of the countrys largest metropolitan areas. With a population of 3,792,621, Los Angeles is the most populous city in California and the second most populous in the United States. South of Los Angeles and with a population of 1,307,402 is San Diego, the second most populous city in the state and the eighth most populous in the nation. The counties of Los Angeles, Orange, San Diego, San Bernardino, and Riverside are the five most populous in the state, the motion picture, television, and music industry are centered in the Los Angeles area in Southern California. Hollywood, a district within Los Angeles, gives its name to the American motion picture industry, headquartered in Southern California are The Walt Disney Company, Sony Pictures, Universal, MGM, Paramount Pictures, 20th Century Fox, and Warner Brothers. Universal, Warner Brothers, and Sony also run major record companies, Southern California is also home to a large homegrown surf and skateboard culture. Companies such as Vans, Volcom, Quiksilver, No Fear, RVCA, some of the worlds biggest action sports events, including the X Games, Boost Mobile Pro, and the U. S. Open of Surfing, are all held in Southern California. Southern California is also important to the world of yachting, the annual Transpacific Yacht Race, or Transpac, from Los Angeles to Hawaii, is one of yachtings premier events. The San Diego Yacht Club held the Americas Cup, the most prestigious prize in yachting, from 1988 to 1995, Southern California is home to many sports franchises and sports networks such as Fox Sports Net. Many locals and tourists frequent the Southern California coast for its popular beaches, the desert city of Palm Springs is popular for its resort feel and nearby open spaces. Southern California is not a geographic designation and definitions of what constitutes Southern California vary. Geographically, Californias North-South midway point lies at exactly 37°958.23 latitude, around 11 miles south of San Jose, however, when the state is divided into two areas, the term Southern California usually refers to the 10 southernmost counties of the state
Southern California
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Southern California Images top from bottom, left to right:
San Diego Skyline,
Downtown Los Angeles,
Village of La Jolla,
Santa Monica Pier,
Surfer at Black's Beach,
Hollywood Sign,
Disneyland,
Hermosa Beach Pier
Southern California
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San Diego Marina district
Southern California
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Sunset in
Venice, a district in Los Angeles
Southern California
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Three Arch Bay in Laguna
2.
Baja California
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Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northernmost and westernmost of the 32 Federal Entities of Mexico, before becoming a state in 1952, the area was known as the North Territory of Baja California. It has an area of 70,113 km2, or 3. 57% of the mass of Mexico and comprises the northern half of the Baja California Peninsula, north of the 28th parallel. The mainland portion of the state is bordered on the west by the Pacific Ocean, on the east by Sonora, the U. S. State of Arizona, and the Gulf of California and its northern limit is the U. S. state of California. The state has an population of 3,165,776 much more than the sparsely populated Baja California Sur to the south. Over 75% of the lives in the capital city, Mexicali, in Ensenada. Other important cities include San Felipe, Rosarito and Tecate, additionally, there is a large immigrant population from the United States due to its proximity to San Diego and the cheaper cost of living compared to San Diego. There is also a significant population from Central America, many immigrants moved to Baja California for a better quality of life and the number of higher paying jobs in comparison to the rest of Mexico and Latin America. Baja California is the twelfth largest state by area in Mexico and its geography ranges from beaches to forests and deserts. The backbone of the state is the Sierra de Baja California, where the Picacho del Diablo and this mountain range effectively divides the weather patterns in the state. In the northwest, the weather is semi-dry and mediterranean, in the narrow center, the weather changes to be more humid due to altitude. It is in area where a few valleys can be found, such as the Valle de Guadalupe. To the east of the range, the Sonoran Desert dominates the landscape. In the south, the weather becomes drier and gives way to the Vizcaino Desert, the state is also home to numerous islands off both of its shores. In fact, the westernmost point in Mexico, the Guadalupe Island, is part of Baja California, the Coronado, Todos Santos and Cedros Islands are also on the Pacific Shore. On the Gulf of California, the biggest island is the Angel de la Guarda, separated from the peninsula by the deep, the first people came to the peninsula at least 11,000 years ago. At that time two main groups are thought to have been present on the peninsula. In the south were the Cochimí, in the north were several groups belonging to the Yuman language family, including the Kiliwa, Paipai, Kumeyaay, Cocopa, and Quechan
Baja California
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Central Desert in Cataviña
Baja California
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Flag
Baja California
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Isla Partida, which is part of the
San Lorenzo Marine Archipelago National Park
Baja California
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Sierra de San Pedro Martir, with Picacho del Diablo in the center.
3.
Great Basin
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The Great Basin is the largest area of contiguous endorheic watersheds in North America. The region spans several physiographic divisions, biomes/ecoregions, and deserts, the term Great Basin is applied to hydrographic, biological, floristic, physiographic, topographic, and ethnographic geographic areas. The name was coined by John C. Frémont, who, based on information gleaned from Joseph R. Walker as well as his own travels, the hydrographic definition is the most commonly used, and is the only one with a definitive border. The other definitions yield not only different geographical boundaries of Great Basin regions, the Great Basin physiographic section is a geographic division of the Basin and Range Province defined by Nevin Fenneman in 1931. The United States Geological Survey adapted Fennemans scheme in their Physiographic division of the United States, the section is somewhat larger than the hydrographic definition. The culture area covers approximately 400,000 sq mi, or just less than twice the area of the hydrographic Great Basin, the hydrographic Great Basin is a 209,162 square miles area that drains internally. All precipitation in the region evaporates, sinks underground or flows into lakes, as observed by Frémont, creeks, streams, or rivers find no outlet to either the Gulf of Mexico or the Pacific Ocean. The region is bounded by the Wasatch Mountains to the east, the Sierra Nevada and Cascade Ranges to the west, the south rim is less distinct. The Great Basin includes most of Nevada, half of Utah, substantial portions of Oregon and California and small areas of Idaho, Wyoming, the term Great Basin is slightly misleading, the region is actually made up of many small basins. The Great Salt Lake, Pyramid Lake, and the Humboldt Sink are a few of the drains in the Great Basin, the Salton Sink is another closed basin within the Great Basin. The Great Basin Divide separates the Great Basin from the watersheds draining to the Pacific Ocean, the southernmost portion of the Great Basin is the watershed area of the Laguna Salada. The Great Basins longest and largest river is the Bear River of 350 mi, Lake Tahoe, North Americas largest alpine lake, is part of the Great Basins central Lahontan subregion. The hydrographic Great Basin contains multiple deserts and ecoregions, each with its own set of flora. The ecological boundaries and divisions in the Great Basin are unclear, the Great Basin overlaps four different deserts, portions of the hot Mojave and Colorado Deserts to the south, and the cold Great Basin and Oregon High Deserts in the north. The deserts can be distinguished by their plants, the Joshua tree and creosote bush occur in the hot deserts, the cold deserts are generally higher than the hot, and have their precipitation spread throughout the year. The climate and flora of the Great Basin is strongly dependent on elevation, as the elevation increases, because of this, forests occur at higher elevations. Utah juniper/single-leaf pinyon and mountain mahogany form open pinyon-juniper woodland on the slopes of most ranges, stands of limber pine and Great Basin bristlecone pine can be found in some of the higher ranges
Great Basin
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The hydrographic Great Basin (magenta outline), distinguished from the
Great Basin Desert (black), and the
Basin and Range Geological Province (teal).
Great Basin
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Relief Map with Great Basin Overlay
Great Basin
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The
Tule Valley watershed and the
House Range (
Notch Peak) are part of the Great Basin's Great Salt Lake
hydrologic unit
Great Basin
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Ecoregions as currently delineated by the Environmental Protection Agency and World Wildlife Fund
4.
Relative humidity
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Relative humidity is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature. Relative humidity depends on temperature and the pressure of the system of interest and it requires less water vapor to attain high relative humidity at low temperatures, more water vapour is required to attain high relative humidity in warm or hot air. Humans are sensitive to high humidity because the body uses evaporative cooling, enabled by perspiration. Perspiration evaporates from the more slowly under humid conditions than under arid. For example, if the air temperature is 24 °C and the humidity is zero percent. If the relative humidity is 100 percent at the air temperature. In other words, if the air is 24 °C and contains saturated water vapor, then the human body cools itself at the rate as it would if it were 27 °C. The heat index and the humidex are indices that reflect the effect of temperature. In cold climates, the temperature causes lower capacity for water vapour to flow about. Dry cracked skin can result from dry air, low humidity causes tissue lining nasal passages to dry, crack and become more susceptible to penetration of Rhinovirus cold viruses. Low humidity is a cause of nosebleeds. The use of a humidifier in homes, especially bedrooms, can help with these symptoms, indoor relative humidities should be kept above 30% to reduce the likelihood of the occupants nasal passages drying out. Humans can be comfortable within a range of humidities depending on the temperature—from thirty to seventy percent—but ideally between 50% and 60%. Very low humidity can create discomfort, respiratory problems, and aggravate allergies in some individuals, in the winter, it is advisable to maintain relative humidity at 30 percent or above. Extremely low relative humidities may also cause eye irritation, wooden furniture can shrink, causing the paint that covers these surfaces to fracture. When the temperature is low and the humidity is high. When relative humidity approaches 100 percent, condensation can occur on surfaces, leading to problems with mold, corrosion, decay, condensation can pose a safety risk as it can promote the growth of mold and wood rot as well as possibly freezing emergency exits shut. The basic principles for buildings, above, also apply to vehicles, in addition, there may be safety considerations
Relative humidity
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Humidity and hygrometry
5.
National Weather Service
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It is a part of the National Oceanic and Atmospheric Administration branch of the Department of Commerce, and is headquartered in Silver Spring, Maryland. The agency was known as the United States Weather Bureau from 1890 until it adopted its current name in 1970, the NWS performs its primary task through a collection of national and regional centers, and 122 local weather forecast offices. As the NWS is a government agency, most of its products are in the public domain, the agency was placed under the Secretary of War as Congress felt military discipline would probably secure the greatest promptness, regularity, and accuracy in the required observations. Within the Department of War, it was assigned to the U. S. Army Signal Service under Brigadier General Albert J. Myer, General Myer gave the National Weather Service its first name, The Division of Telegrams and Reports for the Benefit of Commerce. The agency first became an enterprise in 1890, when it became part of the Department of Agriculture. The first Weather Bureau radiosonde was launched in Massachusetts in 1937, the Bureau would later be moved to the Department of Commerce in 1940. On July 12,1950, bureau chief Francis W, the Weather Bureau became part of the Environmental Science Services Administration when that agency was formed in August 1966. The Environmental Science Services Administration was renamed the National Oceanic and Atmospheric Administration on October 1,1970, at this time, the Weather Bureau became the National Weather Service. NEXRAD, a system of Doppler radars deployed to improve the detection and warning time of local storms, replaced the WSR-57. Bob Glahn has written a history of the first hundred years of the National Weather Service. The NWS, through a variety of sub-organizations, issues different forecast products to users, although, throughout history, text forecasts have been the means of product dissemination, the NWS has been using more forecast products of a digital, gridded, image or other modern format. Each of the 122 Weather Forecast Offices send their graphical forecasts to a server to be compiled in the National Digital Forecast Database. The NDFD is a collection of weather observations used by organizations and the public, including precipitation amount, temperature. Specific points in the database can be accessed using an XML SOAP service. The National Weather Service issues many products relating to wildfires daily, for example, a Fire Weather Forecast, which have a forecast period covering up to seven days, is issued by local Weather Forecast Offices daily, with updates as needed. The forecasts contain weather information relevant to fire control and smoke management for the next 12 to 48 hours, such as direction and speed. The appropriate crews use this information to plan for staffing and equipment levels, the ability to conduct scheduled controlled burns, and assess the daily fire danger. Once per day, NWS meteorologists issue a coded fire weather forecast for specific United States Forest Service observation sites that are input into the National Fire Danger Rating System
National Weather Service
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NWS IMET taking observations in the field.
National Weather Service
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National Weather Service
National Weather Service
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Meteorologists preparing a forecast, early 20th century.
National Weather Service
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An Automated Surface Observing System (ASOS).
6.
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
High-pressure area
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Satellite image of an unusual high-pressure area south of Australia, evidenced by the clearing in the clouds
High-pressure area
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The subtropical ridge shows up as a large area of black (dryness) on this water vapor satellite image from September 2000
High-pressure area
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The Hadley cell carries heat and moisture from the tropics towards the northern and southern mid-latitudes.
7.
Anticyclone
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Effects of surface-based anticyclones include clearing skies as well as cooler, drier air. Fog can also form overnight within a region of higher pressure, sir Francis Galton first discovered anticyclones in the 1860s. Preferred areas within a flow pattern in higher levels of the hydrosphere are beneath the western side of troughs. High-pressure systems are referred to as anticyclones. Their circulation is sometimes referred to as cum sole, subtropical high pressure zones form along the descending portion of the Hadley cell circulation. Upper-level high-pressure areas lie over tropical cyclones due to their warm core nature, surface anticyclones form due to downward 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. Because they weaken with height, these systems are cold. Heating of the earth near the equator forces upward motion and convection along the trough or intertropical convergence zone. The divergence over the near-equatorial trough leads to air rising and moving away from the equator aloft, as air moves towards the mid-latitudes, it cools and sinks leading to subsidence near the 30° parallel of both hemispheres. This circulation known as the Hadley cell forms the subtropical ridge, many of the worlds deserts are caused by these climatological high-pressure areas. Because these anticyclones strengthen with height, they are known as warm core ridges, in the absence of rotation, the wind tends to blow from areas of high pressure to areas of low pressure. The stronger the pressure difference between a system and a low-pressure system, the stronger the wind. The coriolis force caused by Earths rotation gives winds within high-pressure systems their clockwise circulation in the northern hemisphere, friction with land slows down the wind flowing out of high-pressure systems and causes wind to flow more outward from the center. High-pressure systems are associated with light winds at the surface and subsidence of air from higher portions of the troposphere. Subsidence will generally warm an air mass by adiabatic heating, thus, high pressure typically brings clear skies. Because no clouds are present to reflect sunlight during the day, there is more incoming solar radiation, at night, the absence of clouds means that outgoing longwave radiation is not blocked, giving cooler diurnal low temperatures in all seasons. If the surface level relative humidity rises towards 100 percent overnight, the movement of continental arctic air masses to lower latitudes produces strong but vertically shallow high-pressure systems
Anticyclone
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True color satellite image of an unusual anticyclone off southern
Australia in the Southern Hemisphere, on September 8, 2012, showing a counter-clockwise rotation around an oval area of clear skies.
Anticyclone
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Hadley cell circulation tends to create anticyclonic patterns in the
Horse latitudes, depositing drier air and contributing to the world's great deserts.
Anticyclone
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The subtropical ridge shows up as a large area of black (dryness) on this water vapor satellite image from September 2000.
Anticyclone
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Golden Gate Bridge in fog
8.
Katabatic wind
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Such winds are sometimes also called fall winds. Katabatic winds can rush down elevated slopes at speeds, but most are not as intense as that. Not all downslope winds are katabatic, examples of true katabatic winds include the bora in the Adriatic, the Bohemian Wind or Böhmwind in the Ore Mountains, the Santa Ana in southern California, and the oroshi in Japan. Another example is the Barber, an enhanced katabatic wind that blows over the town of Greymouth in New Zealand when there is a southeast flow over the South Island and it is a wind that is known in the area for its coldness. A katabatic wind originates from radiational cooling of air atop a plateau, since the density of air is inversely proportional to temperature, the air will flow downwards, warming approximately adiabatically as it descends. The temperature of the air depends on the temperature in the source region, in the case of the Santa Ana, for example, the wind can become hot by the time it reaches sea level. In Antarctica, by contrast, the wind is still intensely cold, Katabatic winds are most commonly found blowing out from the large and elevated ice sheets of Antarctica and Greenland. The buildup of high density cold air over the ice sheets, where these winds are concentrated into restricted areas in the coastal valleys, the winds blow well over hurricane force, reaching around 300 km/h. In Greenland these winds are called piteraq and are most intense whenever a low pressure area approaches the coast, in a few regions of continental Antarctica the snow is scoured away by the force of the katabatic winds, leading to dry valleys such as the McMurdo Dry Valleys. Since the katabatic winds are descending, they tend to have a low relative humidity, other regions may have a similar but lesser effect, leading to blue ice areas where the snow is removed and the surface ice evaporates, but is replenished by glacier flow from upstream. In the Fuegian Archipelago in South America as well as in Alaska, williwaws originate in the snow and ice fields of the coastal mountains, and they can be faster than 120 knots. Anabatic wind Foehn wind Valley exit jet Bora Giles, Bill, weather A-Z - Katabatic Winds By Bill Giles OBE, BBC, Retrieved 2008-10-14 McKnight, TL & Hess, Darrel. In Physical Geography, A Landscape Appreciation, pp. 131–2, upper Saddle River, NJ, Prentice Hall. ISBN 0-13-020263-0 Parish, Thomas R. Bromwich, David H. Continental-Scale Simulation of the Antarctic Katabatic Wind Regime, Bromwich, David H. Satellite Analyses of Antarctic Katabatic Wind Behavior. Bulletin of the American Meteorological Society, an Extraordinary Katabatic Wind Regime at Terra Nova Bay, Antarctica. Media related to Katabatic wind at Wikimedia Commons
Katabatic wind
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Katabatic wind in Antarctica
9.
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
Low-pressure area
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A clockwise spinning low pressure area or cyclone off southern Australia. The center of the spiral-shaped cloud system is also the center of a low, and usually is where the pressure's lowest.
Low-pressure area
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This low-pressure system over
Iceland spins counter-clockwise due to balance between the Coriolis force and the pressure gradient force.
Low-pressure area
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This depiction of the
Hadley cell shows the process which sustains low-pressure areas. Diverging winds aloft allow for lower pressure and convergence at the Earth's surface, which leads to upward motion.
Low-pressure area
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QuikSCAT image of typical extratropical cyclones over the ocean. Note the maximum winds are on the poleward side of the
occluded front.
10.
Synoptic scale
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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
Synoptic scale
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Golden Gate Bridge in fog
Synoptic scale
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A surface weather analysis for the United States on October 21, 2006.
11.
Sierra Nevada (U.S.)
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The Sierra Nevada is a mountain range in the Western United States, between the Central Valley of California and the Basin and Range Province. The vast majority of the lies in the state of California. The Sierra runs 400 miles north-to-south, and is approximately 70 miles across east-to-west, the Sierra is home to three national parks, twenty wilderness areas, and two national monuments. These areas include Yosemite, Sequoia, and Kings Canyon National Parks, the character of the range is shaped by its geology and ecology. More than one hundred years ago during the Nevadan orogeny. The range started to uplift four M. A. ago, the uplift caused a wide range of elevations and climates in the Sierra Nevada, which are reflected by the presence of five life zones. Uplift continues due to faulting caused by forces, creating spectacular fault block escarpments along the eastern edge of the southern Sierra. The Sierra Nevada has a significant history, the California Gold Rush occurred in the western foothills from 1848 through 1855. Due to inaccessibility, the range was not fully explored until 1912, the Sierra Nevada lies in Central and Eastern California, with a very small but historically important spur extending into Nevada. West-to-east, the Sierra Nevadas elevation increases gradually from 1,000 feet in the Central Valley to an height of about 10,500 feet at its crest only 50–75 miles to the east. The east slope forms the steep Sierra Escarpment, unlike its surroundings, the range receives a substantial amount of snowfall and precipitation due to orographic lift. The Sierra Nevada stretches from the Susan River and Fredonyer Pass in the north to Tehachapi Pass in the south and it is bounded on the west by Californias Central Valley and on the east by the Basin and Range Province. The geographical boundary between the Sierra and the Cascades is virtually indistinguishable, with the Fredonyer Pass designation being traditional, physiographically, the Sierra is a section of the Cascade-Sierra Mountains province, which in turn is part of the larger Pacific Mountain System physiographic division. The range is drained on its western slope by the Central Valley watershed, the northern third of the western Sierra is part of the Sacramento River watershed, and the middle third is drained by the San Joaquin River. The eastern slope watershed of the Sierra is much narrower, its rivers flow out into the endorheic Great Basin of eastern California and western Nevada. Although none of the eastern rivers reach the sea, many of the streams from Mono Lake southwards are diverted into the Los Angeles Aqueduct which provides water to Southern California, the height of the mountains in the Sierra Nevada increases gradually from north to south. Between Fredonyer Pass and Lake Tahoe, the range from 5,000 feet to more than 9,000 feet. The crest near Lake Tahoe is roughly 9,000 feet high, farther south, the highest peak in Yosemite National Park is Mount Lyell
Sierra Nevada (U.S.)
–
The Sierra's
Mills Creek cirque (center) is on the west side of the
Sierra Crest, south of
Mono Lake (top, blue).
Sierra Nevada (U.S.)
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Mount Whitney, the highest peak in the range and the contiguous United States
Sierra Nevada (U.S.)
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The Sierra hosts many waterways, such as the
Tuolumne River.
Sierra Nevada (U.S.)
–
Mount Tallac above
Lake Tahoe
12.
Transverse Ranges
–
The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the end of the California Coast Ranges. They derive the name Transverse Ranges due to their east–west orientation, most of the system lies in the California chaparral and woodlands ecoregion. Lower elevations are dominated by chaparral and scrubland, while higher elevations support large conifer forests, most of the ranges in the system are fault blocks, and were uplifted by tectonic movements during the Cenozoic Era. Most of the Transverse Ranges are bounded to the north and east by the San Andreas Fault, which separates the ranges from the California Coast Ranges, notable passes along the fault include Tejon Pass, Cajon Pass, and San Gorgonio Pass. Components of Transverse Ranges to the north of the include the Tehachapi Mountains. The western and southern boundaries are generally acknowledged to be the Pacific Ocean and various alluvial valleys, major passes not along the San Andreas Fault include Gaviota Pass, San Marcos Pass, the Conejo Grade, Newhall Pass, and Cahuenga Pass. The mountains are notable for being steep and difficult to traverse across, on its northern end, there are few passes that are sufficiently low or wide enough to accommodate significant volumes of traffic. This results in significant traffic issues throughout Southern California when a pass has to be shut due to heavy snow or construction. Occasionally, such as Santa Barbara during the 2005 La Conchita landslide, the Transverse Ranges manifest themselves as a series of roughly parallel ridges with an average height of 3, 000–8,000 feet. They begin at Point Conception in Santa Barbara County, and include the Santa Ynez Mountains that run parallel to the coast behind Santa Barbara. Also in Santa Barbara County, they include the San Rafael Mountains, the Ranges include the steep San Gabriel Mountains northeast of Los Angeles, the San Rafael Hills, Puente Hills, San Jose Hills, and Chino Hills, and the San Bernardino Mountains. The Mojave Desert and Californias low desert, including the Coachella Valley, are at the end of the ranges. The northern Channel Islands of California are also part of the Transverse Ranges, San Miguel, Santa Rosa, Santa Cruz, snow falls above 6,000 feet most winters, and above 3,000 feet every few years. It is rare for elevations above 8,000 feet to go multiple winters without snow, the tree line lies at about 11,000 feet, San Gorgonio Mountain is the only peak with an alpine environment. The Transverse Ranges have a geological history, and the rock composition of the ranges are varied. The Transverse Ranges represent a complex of tectonic forces and faulting stemming from the interaction of the Pacific Plate, the San Andreas Fault is a dextral strike-slip fault with a right step, causing the mountains. Their elevation is somewhat better understood as a consequence of this step, the crust atop the Pacific Plate south of the ranges does not easily make the turn westward as the entire plate moves northwestward, forcing pieces of the crust to compress and lift
Transverse Ranges
–
Snowy
Mount Baden-Powell in the
San Gabriel Mountains
Transverse Ranges
–
The Ranges rise steeply above major urban areas such as Los Angeles
Transverse Ranges
–
Eastern portion of the San Bernardino and San Gabriel Mountains, with the
Mojave Desert on the right and
Silverwood Lake near the boundary. The
San Andreas Fault runs straight up the middle toward the horizon.
Transverse Ranges
–
Savannah-like oak woodlands are typical of the westernmost ranges; shown here is the north slope of the
Santa Ynez Mountains
13.
Cajon Pass
–
Cajon Pass is a mountain pass between the San Bernardino Mountains and the San Gabriel Mountains in Southern California in the United States. It was created by the movements of the San Andreas Fault, located in the Mojave Desert, the pass is an important link from the Greater San Bernardino Area to the Victor Valley, and northeast to Las Vegas. Cajon Pass is at the head of Horsethief Canyon, traversed by California State Route 138 and railroad tracks owned by BNSF Railway, Railroad improvements in 1972 reduced its maximum elevation from about 3,829 feet to 3,777 feet while also reducing the curvature. Interstate 15 does not traverse Cajon Pass, but rather the nearby Cajon Summit, 34°20′58″N 117°26′47″W, however, the entire area including Cajon Pass and Cajon Summit is often collectively called Cajon Pass. Sometimes the entire area is called Cajon Pass, but a distinction is made between Cajon Pass and Cajon Summit in detail, in 1851, a group of Mormon settlers led by Amasa M. Lyman and Charles C. Rich traveled through the Cajon Pass in covered wagons on their way from Salt Lake City to southern California, a prominent rock formation in the pass, where the Mormon trail and the railway merge, is known as Mormon Rocks. In Spanish, the word refers to a box or drawer. The name of the pass is derived from the Spanish land grant that encompassed the area, the Cajon Pass area is known for high wind, turbulence and fog. The weather over the pass can vary, from foggy days with poor visibility to clear afternoons where aircraft are bounced by gusting Santa Ana winds that top 80 mph. The wind in this area is predominantly out of the west, although in Santa Ana, Air spilling over the San Gabriels can cause fairly violent up- and downdrafts. Its important to note that the mass and wing loading of an aircraft determines its sensitivity to turbulence, in the 2006 Mercy Air 2 accident, an air ambulance helicopter collided with mountainous terrain near the pass in foggy weather. The California Southern Railroad, a subsidiary of the Atchison, Topeka, the rail line through the pass was built in the early 1880s as part of a connection between the present day cities of Barstow and San Diego. Today the Union Pacific Railroad and BNSF Railway use the pass to reach Los Angeles, due to the many trains, noteworthy scenery and easy access, it is a popular location for railfans, and numerous photographs of trains on Cajon Pass appear in books and magazines about trains. The Union Pacific Railroad operates and owns one track through the pass, on the previous Southern Pacific Railroad Palmdale cutoff, the BNSF Railway had two tracks and began to operate a third main track in the summer of 2008. The railroads share track rights through the pass ever since the Union Pacific gained track rights on the Santa Fe portion negotiated under the original Los Angeles and Salt Lake Railroad. The original BNSF line was constructed in the 1880s and later roads, U. S. Route 66 and I-15, the second track, built in 1913, is 2 miles longer to get a lower 2. 20% grade. It ran through two tunnels, but both were removed when the third main track was added next to the 1913 line. Trains may be traveling at speeds of 60 and 70 mph on the straighter track away from the pass
Cajon Pass
–
I-15 passing over Cajon Summit in the Cajon Pass area
Cajon Pass
–
Mormon Rocks
Cajon Pass
–
Located at the Highway 138 and Interstate 15 junction, the Mormon Rocks are visual evidence of the San Andreas fault lying beneath the California surface.
Cajon Pass
–
Santa Fe R.R. train going through Cajon Pass in the San Bernardino Mountains 1943
14.
San Gorgonio Pass
–
San Gorgonio Pass, sometimes referred to as Banning Pass due to the location of Banning, California at the western end of the pass, el. Like Cajon Pass to the northwest, it was created by the San Andreas Fault, with the valleys leading up to the pass aligned with the fault. The pass is not as steep as Cajon or Tejon passes, San Gorgonio Mountain, taller but farther away and less visible, is at the northern side of the pass, and Mount San Jacinto is on the southern side. Mount San Jacinto has the fifth-largest rock wall in North America, the pass is the major geologic divide between the igneous batholithic Peninsular Ranges and the Transverse Ranges, which is a massive fault block composed of more diverse forms of rock. According to Yule 2009, the pass is the single largest discontinuity along the San Andreas fault, were faulting not to occur, the Peninsular Ranges would have been contiguous with the Sierra Nevada. Eastward from here, the route descends steeply towards the Coachella Valley, with the end of the pass taken to be at the junction of Interstate 10. The Southern Pacific Railroad laid down tracks through the pass in 1875, there are still portions of the old U. S.99 route between Whitewater Canyon and Cabazon. Main Street in Cabazon, Ramsey Street in Banning, 6th Street in Beaumont, the San Gorgonio Pass area tends to get snow at least once or twice during the winter months, although it rarely sticks to hard surfaces, such as the freeway or city streets. The most famous sight on San Gorgonio Pass is the San Gorgonio Pass Wind Farm on its eastern slope, also nearby are the Cabazon Dinosaurs on the north side of the freeway from Cabazon. San Gorgonio Pass Historical Society website
San Gorgonio Pass
–
A small segment of the San Gorgonio Pass wind farm
15.
Gale force
–
The Beaufort scale /ˈboʊfərt/ is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale, the scale was devised in 1805 by Irish-born Francis Beaufort, a Royal Navy officer, while serving on HMS Woolwich. Beaufort succeeded in standardizing the scale, in 1916, to accommodate the growth of steam power, the descriptions were changed to how the sea, not the sails, behaved and extended to land observations. Rotations to scale numbers were standardized only in 1923, george Simpson, C. B. E. director of the UK Meteorological Office, was responsible for this and for the addition of the land-based descriptors. The measure was slightly altered some decades later to improve its utility for meteorologists, the Beaufort scale was extended in 1946, when forces 13 to 17 were added. However, forces 13 to 17 were intended to only to special cases. Nowadays, the scale is only used in Taiwan and mainland China. Internationally, WMO Manual on Marine Meteorological Services defined the Beaufort Scale only up to force 12 and there was no recommendation on the use of the extended scale. Wind speed on the 1946 Beaufort scale is based on the relationship, v =0.836 B3/2 m/s Where v is the equivalent wind speed at 10 metres above the sea surface. For example, B =9.5 is related to 24.5 m/s which is equal to the limit of 10 Beaufort. Using this formula the highest winds in hurricanes would be 23 in the scale, however, the extended Beaufort numbers above 13 do not match the Saffir–Simpson scale. Wave heights in the scale are for conditions in the open ocean, the wind speeds in different units are not mathematically equivalent, e. g. 12–19 km/h is not equivalent to 8–12 mph, and both are not equivalent to 7–10 knots. The reason is that the Beaufort scale is not an exact nor an objective scale and it was based on visual and subjective observation of a ship and of the sea. The corresponding integral wind speeds were determined later, but the values in different units were never made equivalent. The scale is used in the Shipping Forecasts broadcast on BBC Radio 4 in the United Kingdom, and in the Sea Area Forecast from Met Éireann, Met Éireann issues a Small Craft Warning if winds of Beaufort force 6 are expected up to 10 nautical miles offshore. This scale is widely used in the Netherlands, Germany, Greece, China, Taiwan, Hong Kong, Malta and Macau. Taiwan uses the Beaufort scale with the extension to 17 noted above, China also switched to this extended version without prior notice on the morning of 15 May 2006, and the extended scale was immediately put to use for Typhoon Chanchu. Hong Kong and Macau however keep using force 12 as the maximum, a set of red warning flags and red warning lights is displayed at shore establishments which coincide with the various levels of warning
Gale force
–
Force 12 at sea.
Gale force
–
Sir Francis Beaufort
Gale force
16.
Orographic lift
–
Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, precipitation induced by orographic lift occurs in many places throughout the world. Examples include, The Mogollon Rim in central Arizona The western slope of the Sierra Nevada range in California The mountains near Baja California North – specifically La Bocana to Laguna Hanson, the windward slopes of Khasi and Jayantia Hills in the state of Meghalaya in India. The Western Highlands of Yemen, which receive by far the most rain in Arabia, the Western Ghats that run along Indias western coast. The Great Dividing Range of Eastern and South Eastern Australia which forces uplift of moist air originating from the ocean to the east, the mountains of New Zealand, which faces a prevailing westerly flow off the Tasman Sea. The mountains of western Tasmania which also face a prevailing westerly flow, the southern Andes, which faces a prevailing westerly flow off the Pacific Ocean. The Northwestern United States and Canada see prevailing westerly flow off the northern Pacific Ocean, places on the sea-facing side of coastal mountains see in excess of 140 inches of precipitation per year. These locales are on the side of the mountains which are in the path of storm systems, the ski country region of New York and Pennsylvania, particularly with lake effect snows. Transylvania County, North Carolina, which gets the most rainfall of anywhere in the Eastern U. S, the Appalachian Mountains in West Virginia. Table Mountain, Cape Town, South Africa, the Front Range Foothills of Northern Colorado – west of Boulder to Golden as storms pass by. Winter storms can produce 5–6 feet of snow, the highest precipitation amounts are found slightly upwind from the prevailing winds at the crests of mountain ranges, where they relieve and therefore the upward lifting is greatest. As the air descends the lee side of the mountain, it warms and dries, on the lee side of the mountains, sometimes as little as 15 miles away from high precipitation zones, annual precipitation can be as low as 8 inches per year. The entire island of Kahoolawe is in the shadow of Maui North East England is in the rain shadow of the Pennines. This explains the significant differences between the rainfall in the North West and North East, the Judean Desert in the Land of Israel and the Dead Sea. Downslope winds occur on the side of mountain barriers when a stable air mass is carried over the mountain by strong winds that increase in strength with height. Moisture is removed and latent heat released as the air mass is orographically lifted, as the air mass descends, it is compression heated. As air flows over mountain barriers, orographic lift can create a variety of cloud effects, orographic fog is formed as the air rises up the slope and will often envelope the summit. When the air is humid, some of the moisture will fall on the windward slope, when there is a high wind, a banner cloud is formed downwind of the upper slopes of isolated, steep-sided mountains
Orographic lift
Orographic lift
–
Windy evening
twilight enhanced by the Sun's angle, can visually mimic a
tornado resulting from orographic lift
Orographic lift
–
Wave clouds.
Orographic lift
–
Banner cloud formation on the
Matterhorn
17.
QuikSCAT
–
The NASA QuikSCAT is an Earth observation satellite carrying the SeaWinds scatterometer. Its primary mission is to measure the wind speed and direction over the ice-free global oceans. This SeaWinds scatterometer is referred to as the QuikSCAT scatterometer to distinguish it from the nearly identical SeaWinds scatterometer flown on the ADEOS-2 satellite, QuikSCAT was launched on 19 June 1999 with an initial 3-year mission requirement. QuikSCAT was a recovery mission replacing the NASA Scatterometer, which failed prematurely in June 1997 after just 9.5 months in operation. The QuikSCAT geophysical data record spans from 19 July 1999 to 21 November 2009, because of its wide swath and lack of in-swath gaps, QuikSCAT was able to collect at least one vector wind measurement over 93% of the Worlds Oceans each day. This improved significantly over the 77% coverage provided by NSCAT, each day, QuikSCAT recorded over 400,000 measurements of wind speed and direction. This is hundreds of more surface wind measurements than are collected routinely from ships. QuikSCAT provided measurements of the speed and direction referenced to 10 meters above the sea surface at a spatial resolution of 25 km. Wind information cannot be retrieved within 15–30 km of coastlines or in the presence of sea ice, precipitation generally degrades the wind measurement accuracy, although useful wind and rain information can still be obtained in mid-latitude and tropical cyclones for monitoring purposes. It can, however, still measure radar backscatter at an azimuth angle. A NASA Senior Review panel in 2011 endorsed the continuation of the QuikSCAT mission with these objectives through 2013. SeaWinds uses a dish antenna with two spot beams that sweep in a circular pattern. The antenna consists of a 1-meter diameter rotating dish that produces two spot beams, sweeping in a circular pattern and it radiates 110 W microwave pulses at a pulse repetition frequency of 189 Hz. QuikSCAT operates at a frequency of 13.4 GHz, which is in the Ku-band of microwave frequencies, at this frequency, the atmosphere is mostly transparent to non-precipitating clouds and aerosols, although rain produces significant alteration of the signal. The spacecraft is in an orbit, with equatorial crossing times of ascending swaths at about 06,00 LST ±30 minutes. Along the equator, consecutive swaths are separated by 2,800 km, QuikSCAT orbits Earth at an altitude of 802 km and at a speed of about 7 km per second. Scatterometers such as QuikSCAT emit pulses of microwave radiation and measure the power reflected back to its receiving antenna from the wind-roughened sea surface. Gravity and capillary waves on the sea caused by the wind reflect or backscatter power emitted from the scatterometer radar primarily by means of a Bragg resonance condition
QuikSCAT
–
Artist conception of QuikSCAT
QuikSCAT
–
Launch of the Titan II on June 19, 1999
QuikSCAT
–
QuikSCAT image of
Hurricane Katrina on August 28, 2005 over the
Gulf of Mexico
18.
Foehn wind
–
A föhn or foehn is a type of dry, warm, down-slope wind that occurs in the lee of a mountain range. It is a rain shadow wind that results from the subsequent adiabatic warming of air that has dropped most of its moisture on windward slopes. As a consequence of the different adiabatic rates of moist and dry air. Föhn winds can raise temperatures by as much as 14 °C in just a matter of minutes, Central Europe enjoys a warmer climate due to the Föhn, as moist winds off the Mediterranean Sea blow over the Alps. In German-speaking countries, where popular superstition attributes all kinds of illnesses to various movements of air, there is no scientific proof of such a link. Winds of this type are also called snow-eaters for their ability to make snow melt or sublimate rapidly, Föhn winds are notorious among mountaineers in the Alps, especially those climbing the Eiger, for whom the winds add further difficulty in ascending an already difficult peak. They are also associated with the spread of wildfires, making some regions which experience these winds particularly fire-prone. Anecdotally, residents in areas of frequent föhn winds report a variety of illnesses ranging from migraines to psychosis, the first clinical review of these effects was published by the Austrian physician Anton Czermak in the 19th century. A study by the Ludwig-Maximilians-Universität München found that suicide and accidents increased by 10 percent during föhn winds in Central Europe, the causation of Föhnkrankheit is yet unproven. Labeling for preparations of aspirin combined with caffeine, codeine and the like will sometimes include Föhnkrankheit amongst the indications, evidence for effects from Chinook winds remain anecdotal. The condition exists because warm moist air rises through orographic lifting up, because atmospheric pressure decreases as altitude increases, the air expands and cools adiabatically at the dry adiabatic lapse rate to the point that the air reaches its dew point. Dew point is the temperature at which condensation begins at a given pressure, condensation is also commonly followed by precipitation on the top and windward sides of the mountain. As the air descends on the side, it is warmed by adiabatic compression at the dry adiabatic lapse rate. Because the air has lost much of its water vapor content. The name Foehn arose in the Alpine region, in the Southern Alps, the phenomenon is known as föhn but also Italian, favonio and Slovene, fen. The German word Fön, a trademark, also means hairdryer. Regionally, these winds are known by different names. Often associated with orographic lifting on the windward side of the escarpment Föhn in Ostrobothnia and Western Lapland in Finland as moist air crosses Scandinavian Mountains
Foehn wind
–
How a föhn is produced
Foehn wind
–
Föhn can be initiated when deep low pressures move into Europe drawing moist
Mediterranean air over the
Alps.
19.
Chinook wind
–
Chinook is claimed by popular folk-etymology to mean ice-eater, but it is really the name of the people in the region where the usage was first derived. The reference to a wind or weather system, simply a Chinook, a strong Chinook can make snow one foot deep almost vanish in one day. The snow partly melts and partly evaporates in the dry wind, Chinook winds have been observed to raise winter temperature, often from below -20 °C to as high as 10-20 °C for a few hours or days, then temperatures plummet to their base levels. The greatest recorded temperature change in 24 hours was caused by Chinook winds on January 15,1972, in Loma, Montana, the temperature rose from -48 to 9 °C. Chinooks are most prevalent over southern Alberta in Canada, especially in a belt from Pincher Creek and Crowsnest Pass through Lethbridge, john in northeastern British Columbia, and as far south as Albuquerque, New Mexico. In southwestern Alberta, Chinook winds can gust in excess of hurricane force 120 km/h, on November 19,1962, an especially powerful Chinook in Lethbridge gusted to 171 km/h. In Pincher Creek, the rose by 41 °C, from −19 to 22 °C. Trains have been known to be derailed by Chinook winds, during the winter, driving can be treacherous, as the wind blows snow across roadways, sometimes causing roads to vanish and snowdrifts to pile up higher than a metre. Empty semitrailer trucks driving along Highway 3 and other routes in southern Alberta have been blown over by the high gusts of wind caused by Chinooks. Calgary, Alberta also gets many Chinooks – the Bow Valley in the Canadian Rockies west of the city acts as a wind tunnel. On 27 February 1992, Claresholm, Alberta a small city just south of Calgary and these are some Canadas highest February temperatures. The Chinook can seem to do battle with the Arctic air mass at times and it is not unheard of for people in Lethbridge to complain of −20 °C temperatures while those in Cardston, just 77 km down the road, enjoy 10 °C temperatures. This clash of temperatures can remain stationary, or move back and forth, in the case causing such fluctuations as a warm morning, a bitterly cold afternoon. A curtain of fog often accompanies the clash between warm to the west and cold to the east, one of its most striking features is the Chinook arch, which is a band of stationary stratus clouds caused by air rippling over the mountains due to orographic lifting. To those unfamiliar with it, the Chinook arch may look like a storm cloud at times. However, they rarely produce rain or snow and they can also create stunning sunrises and sunsets. The stunning colours seen in the Chinook arch are quite common, the Chinook is a föhn wind, a rain shadow wind which results from the subsequent adiabatic warming of air which has dropped most of its moisture on windward slopes. As a consequence of the different adiabatic rates of moist and dry air, the dried air then descends on the leeward side of the mountains, warming at the dry adiabatic rate of 10 °C/1000 m
Chinook wind
–
Adiabatic warming of downward moving air produces the warm Chinook wind
Chinook wind
Chinook wind
–
Chinook arch over Calgary, January 6, 2003
Chinook wind
–
Chinook arch over Calgary, March 2007
20.
Heat capacity
–
Heat capacity or thermal capacity is a measurable physical quantity equal to the ratio of the heat added to an object to the resulting temperature change. The unit of capacity is joule per kelvin J K. Specific heat is the amount of heat needed to raise the temperature of one kilogram of mass by 1 kelvin, Heat capacity is an extensive property of matter, meaning it is proportional to the size of the system. The molar heat capacity is the capacity per unit amount of a pure substance. In some engineering contexts, the heat capacity is used. Other contributions can come from magnetic and electronic degrees of freedom in solids, for quantum mechanical reasons, at any given temperature, some of these degrees of freedom may be unavailable, or only partially available, to store thermal energy. In such cases, the capacity is a fraction of the maximum. As the temperature approaches zero, the heat capacity of a system approaches zero. Quantum theory can be used to predict the heat capacity of simple systems. In a previous theory of common in the early modern period, heat was thought to be a measurement of an invisible fluid. Bodies were capable of holding an amount of this fluid, hence the term heat capacity, named. Heat is no longer considered a fluid, but rather a transfer of disordered energy, nevertheless, at least in English, the term heat capacity survives. In some other languages, the thermal capacity is preferred. In the International System of Units, heat capacity has the unit joules per kelvin, if the temperature change is sufficiently small the heat capacity may be assumed to be constant, C = Q Δ T. Heat capacity is a property, meaning it depends on the extent or size of the physical system studied. A sample containing twice the amount of substance as another sample requires the transfer of twice the amount of heat to achieve the change in temperature. For many purposes it is convenient to report heat capacity as an intensive property. In practice, this is most often an expression of the property in relation to a unit of mass, in science and engineering, International standards now recommend that specific heat capacity always refer to division by mass
Heat capacity
Heat capacity
–
Molecules undergo many characteristic internal vibrations. Potential energy stored in these internal degrees of freedom contributes to a sample’s energy content, but not to its temperature. More internal degrees of freedom tend to increase a substance's specific heat capacity, so long as temperatures are high enough to overcome quantum effects.
21.
Chaparral
–
Chaparral is a shrubland or heathland plant community found primarily in the U. S. state of California and in the northern portion of the Baja California Peninsula, Mexico. Chaparral covers 5 percent of the state of California, and associated Mediterranean shrubland an additional 3.5 percent, the name comes from the Spanish word for scrub oak, chaparro. In its natural state, chaparral is characterized by infrequent fires, mature chaparral is characterized by nearly impenetrable, dense thickets. They grow as woody shrubs with hard and small leaves, are non-leaf-dropping, after the first rains following a fire, the landscape is dominated by soft-leaved non-woody annual plants, known as fire followers, which die back with the summer dry period. According to the California Academy of Sciences, Mediterranean shrubland contains more than 20 percent of the plant diversity. The word chaparral is a word from Spanish chaparro, meaning both small and dwarf evergreen oak, which itself comes from the Basque word txapar, with exactly the same meaning. In Central and Southern California chaparral forms a dominant habitat, the following is a short list of birds which are an integral part of the cismontane chaparral ecosystems. Transmontane chaparral features xeric desert climate, not Mediterranean climate habitats, Desert chaparral is a regional ecosystem subset of the deserts and xeric shrublands biome, with some plant species from the California chaparral and woodlands ecoregion. Unlike cismontane chaparral, which forms dense, impenetrable stands of plants, desert chaparral is open, individual shrubs can reach up to 10 feet in height. Transmontane chaparral or desert chaparral is found on the slopes of major mountain range systems on the western sides of the deserts of California. It is distinguished from the cismontane chaparral found on the side of the mountains. Naturally, desert chaparral experiences less rainfall than cismontane chaparral. Plants in this community are characterized by small, hard evergreen leaves, Desert chaparral grows above Californias desert cactus scrub plant community and below the pinyon-juniper woodland. It is further distinguished from the deciduous sub-alpine scrub above the pinyon-juniper woodlands on the side of the Peninsular ranges. Transmontane chaparral typically grows on the northern slopes of the southern Transverse Ranges. It can also be found in higher-elevation sky islands in the interior of the deserts, there is overlap of animals with those of the adjacent desert and pinyon-juniper communities. Canis latrans, coyotes Lynx rufus, bobcats Neotoma sp, the Chaparral area receives about 38–100 cm of precipitation a year. This makes the chaparral most vulnerable to fire in the late summer, the chaparral ecosystem as a whole is adapted to be able to recover from infrequent wildfires, indeed, chaparral regions are known culturally and historically for their impressive fires
Chaparral
–
Chaparral, Santa Ynez Mountains, near Santa Barbara, California
Chaparral
–
Southern coastal scrub in the
Santa Monica Mountains National Recreation Area
Chaparral
–
View from the
Laguna Mountains, chaparral in the foreground
22.
Wildfire
–
A wildfire or wildland fire is a fire in an area of combustible vegetation that occurs in the countryside or rural area. Fossil charcoal indicates that wildfires began soon after the appearance of terrestrial plants 420 million years ago, wildfire’s occurrence throughout the history of terrestrial life invites conjecture that fire must have had pronounced evolutionary effects on most ecosystems flora and fauna. Earth is an intrinsically flammable planet owing to its cover of vegetation, seasonally dry climates, atmospheric oxygen. Wildfires can be characterized in terms of the cause of ignition, their properties, the combustible material present. Wildfires can cause damage to property and human life, but they have beneficial effects on native vegetation, animals. Many plant species depend on the effects of fire for growth, however, wildfire in ecosystems where wildfire is uncommon or where non-native vegetation has encroached may have negative ecological effects. Wildfire behaviour and severity result from the combination of such as available fuels, physical setting. Strategies of wildfire prevention, detection, and suppression have varied over the years, one common and inexpensive technique is controlled burning, permitting or even igniting smaller fires to minimize the amount of flammable material available for a potential wildfire. Vegetation may be burned periodically to maintain species diversity and frequent burning of surface fuels limits fuel accumulation. Wildland fire use is the cheapest and most ecologically appropriate policy for many forests, fuels may also be removed by logging, but fuels treatments and thinning have no effect on severe fire behavior. Wildfires can also be started in communities experiencing shifting cultivation, where land is cleared quickly and farmed until the soil loses fertility, forested areas cleared by logging encourage the dominance of flammable grasses, and abandoned logging roads overgrown by vegetation may act as fire corridors. The most common cause of wildfires throughout the world. In Canada and northwest China, for example, lightning operates as the source of ignition. In other parts of the world, human involvement is a major contributor, in China and in the Mediterranean Basin, human carelessness is a major cause of wildfires. In the United States and Australia, the source of wildfires can be traced both to lightning strikes and to human activities. Coal seam fires burn in the thousands around the world, such as those in Burning Mountain, New South Wales, Centralia, Pennsylvania and they can also flare up unexpectedly and ignite nearby flammable material. The spread of wildfires based on the flammable material present, its vertical arrangement and moisture content. Fuel arrangement and density is governed in part by topography, as land shape determines factors such as available sunlight, overall, fire types can be generally characterized by their fuels as follows, Ground fires are fed by subterranean roots, duff and other buried organic matter
Wildfire
–
A
wildfire in California on September 5, 2008
Wildfire
–
A surface fire in the western desert of
Utah, U.S.
Wildfire
–
Charred landscape following a crown fire in the
North Cascades, U.S.
Wildfire
–
Torching of Juniper Tree on the Palisade Wildfire in Nevada
23.
October 2007 California wildfires
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The 2007 California Wildfire Season saw over 9,000 separate wildfires that charred 1,087,110 acres of land. At the peak of the activity in October 2007, the raging wildfires were visible from space. The wildfires killed a total of 14 people, with nine of them dying directly from the fires,160 others were injured, California Governor Arnold Schwarzenegger declared a state of emergency in seven California counties where fires were burning. President George W. Bush concurred, and ordered federal aid to supplement state, the fires forced approximately 1,000,000 people to evacuate from their homes, becoming the largest evacuation in Californias history. Major contributing factors to the fire conditions were drought in Southern California, hot weather. Several were triggered by power lines damaged by the high winds, one fire started when a semi-truck overturned. Another was suspected as having been caused, the suspect was shot. A 10-year-old boy admitted that he started the Buckweed Fire by playing with matches. Causes of the remaining fires remain under investigation, the last fires, the Santiago and Poomacha Fires, were fully contained on November 9,2007, about 19 days after the series of wildfires had begun to ignite. During the season, the National Interagency Fire Center reports that two firefighters were killed, one died via helicopter and the second in a bulldozer rollover. Below is a list of all fires that exceeded 1,000 acres during the 2007 fire season, the list is taken from CAL FIREs list of large fires. Of all the wildfires, the two largest ones were located in San Diego County, the largest, the Witch Creek Fire, burned areas in north and northeast San Diego County. The second largest, the Harris Fire, burned northwest from the U. S–Mexico border towards San Diego, though individually the fires did not surpass the Cedar Fire, if combined as one, they did. Residents were subjected to a mix of mandatory and voluntary evacuations, hundreds of thousands of residents were notified of evacuations via a computerized Reverse 911 phone call system. While this alert system was effective, many residents in Rancho Bernardo received the calls after they had been driven from their homes. On the other hand, in Carmel Valley, only the half was officially evacuated. Law enforcement officers also notified residents by driving through evacuation areas, two days into the fires, approximately 500,000 people from at least 346,000 homes were under mandatory orders to evacuate, the largest evacuation in the regions history. Evacuation sites included Qualcomm Stadium, as well as schools, civic centers
October 2007 California wildfires
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The Poomacha Fire: photo taken looking South towards San Diego from
Temecula
October 2007 California wildfires
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NOAA hot spot map of San Diego County, October 23, 2007.
October 2007 California wildfires
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The skyline of Long Beach, California, looking east on the morning of October 24, 2007, with the sky filled with smoke.
October 2007 California wildfires
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Santa Clarita, California the night of October 21, 2007
24.
Upwelling
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The nutrient-rich upwelled water stimulates the growth and reproduction of primary producers such as phytoplankton. Due to the biomass of phytoplankton and presence of water in these regions, upwelling zones can be identified by cool sea surface temperatures. The increased availability in upwelling regions results in levels of primary productivity. Approximately 25% of the global marine fish catches come from five upwellings that occupy only 5% of the total ocean area. Upwellings that are driven by coastal currents or diverging open ocean have the greatest impact on nutrient-enriched waters, the three main drivers that work together to cause upwelling are wind, Coriolis effects, and Ekman transport. They operate differently for different types of upwelling, but the effects are the same. In the overall process of upwelling, winds blow across the sea surface at a particular direction, as a result of the wind, the water is transported a net of 90 degrees from the direction of the wind due to Coriolis forces and Ekman transport. This results in a spiral of water movement down the water column, then, it is the Coriolis forces that dictate which way the water will move, in the Northern hemisphere, the water is transported to the right of the direction of the wind. In the Southern Hemisphere, the water is transported to the left of the wind, if this net movement of water is divergent, then upwelling of deep water occurs to replace the water that was lost. The major upwellings in the ocean are associated with the divergence of currents that bring deeper, colder, coastal upwelling is the best known type of upwelling, and the most closely related to human activities as it supports some of the most productive fisheries in the world. Wind-driven currents are diverted to the right of the winds in the Northern Hemisphere, the result is a net movement of surface water at right angles to the direction of the wind, known as the Ekman transport. When Ekman transport is occurring away from the coast, surface waters moving away are replaced by deeper, colder, and denser water. Normally, this process occurs at a rate of about 5–10 meters per day. Deep waters are rich in nutrients, including nitrate, phosphate and silicic acid, Upwelling regions therefore result in very high levels of primary production in comparison to other areas of the ocean. They account for about 50% of global marine productivity, high primary production propagates up the food chain because phytoplankton are at the base of the oceanic food chain. All of these currents support major fisheries, the four major eastern boundary currents in which coastal upwelling primarily occurs are the Canary Current, Benguela Current, California Current, and Humboldt Current. The Benguela Current is the boundary of the South Atlantic subtropical gyre. The subsystems are divided by an area of permanent upwelling off of Luderitz, the California Current System is an eastern boundary current of the North Pacific that is also characterized by a north and south split
Upwelling
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Areas of upwelling in red
Upwelling
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If the wind blows parallel to the coast in the northern hemisphere (such as the coast of California, where the wind blows South), then
Ekman transport can produce a net movement of surface water 90° to the right. This may result in coastal upwelling.
Upwelling
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Unusually strong winds from the east push warm (red) surface water towards Africa, allowing cold (blue) water to upwell along the Sumatran coast
Upwelling
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During an
El Niño, wind indirectly drives warm water to the South American coast, reducing the effects of cold upwelling
25.
Chlorophyll
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Chlorophyll is any of several closely related green pigments found in cyanobacteria and the chloroplasts of algae and plants. Its name is derived from the Greek words χλωρός, chloros and φύλλον, chlorophyll is essential in photosynthesis, allowing plants to absorb energy from light. Chlorophyll absorbs light most strongly in the portion of the electromagnetic spectrum. Conversely, it is a poor absorber of green and near-green portions of the spectrum, chlorophyll molecules are specifically arranged in and around photosystems that are embedded in the thylakoid membranes of chloroplasts. Two types of chlorophyll exist in the photosystems of green plants, chlorophyll was first isolated and named by Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817. Chlorophyll is vital for photosynthesis, which plants to absorb energy from light. Chlorophyll molecules are arranged in and around photosystems that are embedded in the thylakoid membranes of chloroplasts. In these complexes, chlorophyll serves two primary functions, the two currently accepted photosystem units are photosystem II and photosystem I, which have their own distinct reaction centres, named P680 and P700, respectively. These centres are named after the wavelength of their red-peak absorption maximum, the identity, function and spectral properties of the types of chlorophyll in each photosystem are distinct and determined by each other and the protein structure surrounding them. Once extracted from the protein into a solvent, these chlorophyll pigments can be separated into chlorophyll a, the function of the reaction center of chlorophyll is to absorb light energy and transfer it to other parts of the photosystem. The absorbed energy of the photon is transferred to an electron in a process called charge separation, the removal of the electron from the chlorophyll is an oxidation reaction. The chlorophyll donates the high energy electron to a series of molecular intermediates called a transport chain. The charged reaction center of chlorophyll is reduced back to its ground state by accepting an electron stripped from water. The electron that reduces P680+ ultimately comes from the oxidation of water into O2 and this reaction is how photosynthetic organisms such as plants produce O2 gas, and is the source for practically all the O2 in Earths atmosphere. Electron transfer reactions in the membranes are complex, however. NADPH is an agent used to reduce CO2 into sugars as well as other biosynthetic reactions. Thus, the other chlorophylls in the photosystem and antenna pigment proteins all cooperatively absorb, besides chlorophyll a, there are other pigments, called accessory pigments, which occur in these pigment–protein antenna complexes. Chlorophyll is a pigment, which is structurally similar to
Chlorophyll
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Chlorophyll gives leaves their green color and absorbs light that is used in photosynthesis.
Chlorophyll
Chlorophyll
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Chlorophyll is found in high concentrations in
chloroplasts of plant cells.
26.
Santa Catalina Island, California
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Santa Catalina Island, often called Catalina Island, or just Catalina, is a rocky island off the coast of the U. S. state of California in the Gulf of Santa Catalina. The island is 22 miles long and 8 miles across at its greatest width, the island is located about 22 miles south-southwest of Los Angeles, California. The highest point on the island is 2,097 feet Mt. Orizaba, Santa Catalina is part of the Channel Islands of California archipelago and lies within Los Angeles County. Catalina was originally settled by Native Americans who called the island Pimugna or Pimu, the first Europeans to arrive on Catalina claimed it for the Spanish Empire. Over the years, territorial claims to the transferred to Mexico. Since the 1970s, most of the island has been administered by the Catalina Island Conservancy and its total population in the 2010 census was 4,096 people,90 percent of whom live in the islands only incorporated city, Avalon. The second center of population is the village of Two Harbors at the islands isthmus. Development occurs also at the settlements of Rancho Escondido and Middle Ranch. The remaining population is scattered over the island between the two population centers, the Tongva called the island Pimu or Pimugna and referred to themselves as the Pimugnans or Pimuvit. Archeological evidence shows Pimugnan settlement beginning in 7000 BC, the Pimugnans had settlements all over the island at one time or another, with their biggest villages being at the Isthmus and at present-day Avalon, Shark/Little Harbor, and Emerald Bay. The Pimugnans were renowned for their mining, working and trade of soapstone which was found in quantities and varieties on the island. This material was in demand and was traded along the California coast. The first European to set foot on the island was the Portuguese explorer Juan Rodríguez Cabrillo, on October 7,1542, he claimed the island for Spain and christened it San Salvador after his ship. Over half a century later, another Spanish explorer, Sebastián Vizcaíno, vizcaino renamed the island in the saints honor. The colonization of California by the Spanish coincided with the decline of the Pimugnans because of diseases brought by them from Europe. By the 1830s, the entire native population had migrated to the mainland to work in the missions or as ranch hands for the many private land owners. Franciscan friars considered building a mission on Catalina, but abandoned the idea because of the lack of water on the island. While Spain maintained its claim on Catalina Island, foreigners were forbidden to trade with colonies, russian hunters from the Aleutian Islands, and America set up camps on Santa Catalina and the surrounding Channel Islands to hunt otters and seals around the island for their pelts
Santa Catalina Island, California
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Santa Catalina Island satellite image
Santa Catalina Island, California
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Juan Rodríguez Cabrillo
Santa Catalina Island, California
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Tourists enjoying the waters off Catalina in 1889
Santa Catalina Island, California
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The
Catalina Casino as it appeared in 2007
27.
Avalon, California
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Avalon is the only incorporated city on Santa Catalina Island of the California Channel Islands, and the southernmost city in Los Angeles County. The population was 3,728 at the 2010 census, Avalon was inhabited in pre-modern times by members of the Gabrielino/Tongva tribe. From the late 19th century to the early 20th century, several different developers tried to develop Avalon into a resort destination community, in 1919, William Wrigley, Jr. gained control of Avalon. Wrigley oversaw much of the development of Avalon, including the construction of the landmark Catalina Casino, the city remains primarily a resort community. Most of the waterfront is dominated by tourism-oriented businesses, the older parts of the town on the valley floor consist primarily of small houses and two and three-story buildings in various traditional architectural styles. Avalon attracts about 1 million visitors a year and is visited by cruise ships. Prior to the era, Avalon Bay was inhabited by people of the Gabrielino/Tongva tribe. The island was a source of soapstone to the Tongva. The Tongva called the island Pimu or Pimugna and referred to themselves as the Pimugnans. However, by the 1830s, the islands native population had either died off. In the 1860s, German immigrant Augustus William Timms ran a sheep herding business on Catalina Island, one of his vessels, the Rosita, would also ferry pleasure seekers across the channel to Avalon Bay for bathing and fishing. The settlement in Avalon was then referred to as Timmss Landing in his honor, by the summer of 1883, there were thirty tents and three wooden buildings at Timmss Landing. The first owner to try to develop Avalon Bay into a destination was George Shatto. Shatto purchased the island for $200,000 from the estate of James Lick at the height of an estate boom in Southern California in 1887. Shatto created the settlement that would become Avalon, and can be credited with building the towns first hotel, the original Hotel Metropole, Shatto laid out Avalons streets, and introduced it as a vacation destination to the general public. Despite Shattos efforts, in a few years he had to default on his loan, the sons of Phineas Banning bought the island in 1891 from the Lick estate and established the Santa Catalina Island Company to develop it as a resort. The Banning brothers fulfilled Shattos dream of making Avalon a resort community and they built a dance pavilion in the center of town, made additions to the Hotel Metropole and steamer-wharf, built an aquarium, created the Pilgrim Club. In 1919, due to related to the 1915 fire and a general decline in tourism during World War I
Avalon, California
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Avalon Harbor
Avalon, California
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Location of Avalon within
Los Angeles County
Avalon, California
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Avalon Bay around 1910, before the construction of the casino
Avalon, California
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William Wrigley, Jr. took control of Avalon in 1919
28.
Two Harbors, California
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Two Harbors, colloquially known as The Isthmus, is a small unincorporated community island village on Santa Catalina Island, California with a population of 298. It is the center of population on the island, besides the city of Avalon. It is mainly a resort village and it has only one restaurant, one hotel, and one general store. The village has about 150 permanent residents who live on the isthmus year-round, one notable feature is the little one-room schoolhouse where those who live on the isthmus can go to school. Two Harbors is an island village located approximately 37 km from San Pedro Harbor on Santa Catalina Island. On the islands narrow isthmus, it is located about 18 miles from the city in the Island. White Rock Island, commonly known as Bird Rock, is a privately owned island only 6312 m² in size. It is approximately 1.4 km northeast of Two Harbors, offshore from Isthmus Cove, the area where Two Harbors is located was originally referred to simply as the Isthmus of Catalina Island. By the 1860s, mining operations for silver, lead and zinc took place in the area, however the reservation idea was abandoned and so was the camp. The Ning Po burned off the shore of the Isthmus in 1938. Two Harbors is part of the Long Beach Unified School District, young children in Two Harbors attend the one-room school, Two Harbors Elementary School in Two Harbors. Older children attend the school and high school at Avalon. The USC Wrigley Institute for Environmental Studies is an environmental research, the facility was made possible by a donation from the Wrigley family and was named for Philip K. Wrigley. Two Harbors is served by lines with regular daily service to San Pedro. A helicopter can also be chartered to the village, the Catalina Airport-In-The-Sky is 10 miles away to the east. Alternatively, various charter boats offer private service to the Island Most people generally walk, to get around the island from Two Harbors, one can get a bus that can take them anywhere on the Island, or one can hike
Two Harbors, California
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View of Two Harbors from 16,000 feet
Two Harbors, California
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Two Harbors; Isthmus Cove on the left of frame, Catalina Harbor on the right.
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