1.
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
2.
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
3.
1968 Atlantic hurricane season
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The 1968 Atlantic hurricane season was one of five Atlantic hurricane seasons during the satellite era not to feature a major hurricane, the others being 1972,1986,1994, and 2013. The season officially began on June 1 and lasted until November 30 and it was a below average season in terms of tropical storms, with a total of eight nameable storms. The first system, Hurricane Abby, developed in the northwestern Caribbean Sea on June 1, Abby moved northward and struck Cuba, bringing heavy rainfall and flooding to western portions of the island. Making landfall in Florida on June 4, Abby caused flooding and spawned four tornadoes, overall, the hurricane resulted in six deaths and about $450,000 in damage. In late June, Tropical Storm Candy brought minor flooding and spawned several tornadoes across portions of the Southern United States, overall damage from the cyclone reached approximately $2.7 million. Despite three named storms in June, cyclone activity slowed throughout the subsequent month, with one tropical depression. During late August and early September, Tropical Depression Eleven brought flooding to the Jacksonville area of Florida, Hurricane Gladys, the final and also the strongest named storm of the season, developed in the southwestern Caribbean Sea on October 13. Rough seas, gusty winds, tornadoes, and heavy rainfall resulted in minor impact in Florida. Gladys also provided relief for one of North Carolinas worst droughts, several other storms left negligible impact on land. Overall, the storms of the season collectively caused approximately $21.8 million in damage, the Atlantic hurricane season officially began on June 1, with Hurricane Abby developing that day. It was an average season in which eight tropical storms formed, compared to the 1966–2009 average of 11.3 named storms. Four of these reached hurricane status, slightly below the 1966–2009 average of 6.2, none of the hurricanes strengthened into a major hurricane, only four other seasons since the satellite era began featured no major hurricanes,1972,1986,1994, and 2013. Further, no hurricanes exceeded Category 1 intensity on the Saffir–Simpson hurricane wind scale, despite an active beginning, this season had the fewest hurricane days since 1962. Four hurricanes and one tropical storm made landfall during the season, causing 17 deaths, the last storm of the season, a tropical depression, dissipated on November 25, five days before the official end of hurricane season on November 30. Tropical cyclogenesis began in June, with three named storms during that month – hurricanes Abby and Brenda and Tropical Storm Candy – tying the record set in 1886,1936, despite the quick start, activity abruptly slowed, with only a tropical depression in July. The next named storm, Hurricane Dolly, existed from August 10 to August 17, September was the most active month, with five tropical depressions, two tropical storms, and one subtropical storm, which peaked with an intensity equivalent to a Category 1. In October, Hurricane Gladys became the strongest tropical cyclone of the season, despite maximum sustained winds of only 85 mph, the seasons activity was reflected with an accumulated cyclone energy rating of 45. It is only calculated for full advisories on tropical systems at or exceeding 39 mph, the interaction of a mid-tropospheric trough and a cold front spawned a tropical depression on June 1
4.
1968 Pacific hurricane season
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The 1968 Pacific hurricane season ties the record for having the most active August in terms of tropical storms. It officially started on May 15,1968, in the eastern Pacific and June 1 in the central Pacific and these dates conventionally delimit the period of each year when most tropical cyclones form in the northeastern Pacific Ocean. Several notable systems formed during the season, five named storms—Hyacinth, Iva, Liza, Naomi, and Pauline—had effects in the United States. Two others—Annette and Tropical Depression Two—affected Mexico, and Tropical Storm Simone made a landfall on Guatemala. Tropical Storm Virginia, which formed in the West Pacific, crossed into the basin at a high latitude, of these, six remained depressions, thirteen peaked as tropical storms, and six reached hurricane strength. There were no major hurricanes this season, many of the tropical cyclones this season – including all six hurricanes – formed from Intertropical Convergence Zone disturbances. Eight tropical storms formed in August this year, a record for the most active August in the East Pacific, the eight named storms forming in August this year also made it the most tropical storms to ever form in a month in the East Pacific since 1966. However, this record was tied during the 2009 Pacific hurricane season, because of a lack of Hurricane Hunter data, a majority of the intensity readings from this season were later removed from the best track file. Even though the James Lykes noted that an area of disturbed weather south of the Pacific coast of Mexico was poorly organized and it made landfall and dissipated near Manzanillo on June 22. The satellite that was orbiting over Annette never took a picture with the storm in view since the storm was usually at the edge of the satellite. A computerized mosaic showed a vortex with the center over land. Damage, if any, is not known, the first of a large group of tropical cyclones that developed from ITCZ disturbances this season, a low pressure center in the ITCZ rapidly developed late on July 3. Becoming a tropical storm on July 4, the received the name Bonny. The newly named storm tracked west-northwest for 24 hours before turning to the overnight on July 5 into July 6. As a result, winds of 60 mph were measured on Socorro Island, at this time, satellites revealed that cooler sea surface temperatures and stratus inflow were starting to take their toll on Bonny. The storm began a slow dissipation and, by the time a ship reported the status of the weakening storm. The storm dissipated on July 9, the remnant low of Bonny had no kinetic energy, causing the forecasters to note that it had a ragged appearance on satellite imagery. The disturbance that became Celeste was first noticed by the Eastern Pacific Hurricane Center on July 13, the disturbance slowly intensified, becoming a tropical depression on July 14 and reaching storm strength on the next day
5.
1966 Pacific typhoon season
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The 1966 Pacific typhoon season was an active season, with many tropical cyclones having severe impacts in China, Japan, and the Philippines. Throughout the year, storms were responsible for at least 997 fatalities and $377.6 million in damage, however and it is widely accepted that wind estimates in the Western North Pacific during the reconnaissance era prior to 1988 are subject to great error. In many cases, intensities were grossly overestimated due to a combination inadequate technology, additionally, methodologies for obtaining wind estimates have changed over the decades and is not the same today as in 1966. Many storms in 1966 received strength reductions as a result of study, however. Notably the number of typhoons, Category 3 equivalent or higher on the Saffir–Simpson hurricane wind scale, was reduced from eight to six. The western Pacific basin covers the Pacific Ocean, north of the equator, Storms that form east of the date line and north of the equator are called hurricanes, see 1966 Pacific hurricane season. Tropical Storms formed in the entire west Pacific basin were assigned a name by the Joint Typhoon Warning Center, the Japan Meteorological Agency also monitored systems in the basin, however, it was not recognized as the Regional Specialized Meteorological Center until 1968. 115 mph Typhoon Irma hit the eastern Samar on May 15 and it weakened over the island, but re-intensified rapidly to a 140 mph typhoon in the Sibuyan Sea before hitting Mindoro on the 17th. After weakening to a storm, Irma turned northward to hit western Luzon as a 95 mph typhoon on the 19th. It accelerated to the northeast, and became extratropical on the 22nd, the extratropical remnant raced northeast before abruptly slowing on May 23 well to the east of Japan. During that time, it turned north while moving erratically. The system later acquired a general eastward track by May 26, severe damage took place across the Philippines, with Leyte suffering the brunt of Irmas impact. Twenty people lost their lives across the country, preliminary reports indicated that Tacloban incurred $2.5 million in damage. A gasoline explosion near Manila that killed 12 people and injured 18 others was partially attributed to the typhoon. On May 17, the 740 ton vessel Pioneer Cebu sailed directly into the storm over the Visayan Sea off the coast of Malapascua Island after ignoring warnings to remain at port, carrying 262 people, the ship struck a reef while battling rough seas in the typhoon. Passengers began abandoning the vessel soon thereafter under the captains orders while message about the ships sinking was relayed by the radio operator. A large wave struck the ship on its side, capsizing and submerging it entirely. Of the passengers and crew,122 went down with the ship, including captain Floro Yap, rescue operations lasted nearly two days, with many of the survivors being stranded in shark infested waters for upwards of 40 hours
6.
1967 Pacific typhoon season
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The 1967 Pacific typhoon season has no official bounds, it ran year-round in 1967, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean, the scope of this article is limited to the Pacific Ocean, north of the equator and west of the international date line. Storms that form east of the line and north of the equator are called hurricanes. Tropical Storms formed in the entire west pacific basin were assigned a name by the Joint Typhoon Warning Center, Tropical depressions in this basin have the W suffix added to their number. Tropical depressions that enter or form in the Philippine area of responsibility are assigned a name by the Philippine Atmospheric and this can often result in the same storm having two names. During the 1967 Pacific typhoon season,40 tropical depressions formed, twenty tropical storms attained typhoon intensity, and five of the typhoons reached super typhoon intensity. Typhoon Violet, which formed on April 1, steadily weakened from its peak of 140 mph to directly impact northeastern Luzon as a 115 mph typhoon on the 8th and it dissipated in the South China Sea on April 12 without causing any significant damage. Typhoon Billie, having developed on July 2, reached its peak of 85 mph on July 5, a cold core low developed tropical characteristics and became Tropical Depression 8W on July 6. It tracked westward, becoming a storm later that day. After briefly weakening to a storm, Clara re-attained typhoon status. Clara weakened to a 90 mph typhoon just before hitting Taiwan on the 11th, claras heavy rains caused 69 fatalities and a further 32 people to be reported as missing. Super Typhoon Opal was a system that peaked in winds of 180 miles per hour. On September 14, Tropical Storm Sarah, which formed across the International Date Line, immediately after the first advisory following Sarahs entrance into the West Pacific, it was upgraded to a minimal typhoon. Typhoon Sarah continued to intensify, and late on September 15, the next day, Sarah reached its peak intensity, attaining 150 mph winds and a 932 millibar pressure reading, making the system a super typhoon. Sarah began gradually weakening afterwards, and late on September 21, it became extratropical, on September 16, Sarah made landfall on Wake Island at peak intensity, causing widespread damage. Coincidentally, Olives attack on the island occurred on September 16, Carla became an intense typhoon while located in the Philippine Sea on October 15. During its weakening stage, the typhoon dumped extreme rainfall around its circulation, Typhoon Emma was the second super Typhoon to hit the Philippines in just weeks after Typhoon Carla. Typhoon Emma left 300 people dead and 60 others missing 1967 Atlantic hurricane season 1967 Pacific hurricane season Japan Meteorological Agency Joint Typhoon Warning Center
7.
1969 Pacific typhoon season
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The 1969 Pacific typhoon season was the third least-active season on record. The season had no bounds, it ran year-round in 1969. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean, the scope of this article is limited to the Pacific Ocean, north of the equator and west of the international date line. Storms that form east of the line and north of the equator are called hurricanes. Tropical Storms formed in the entire west pacific basin were assigned a name by the Joint Typhoon Warning Center, Tropical depressions in this basin have the W suffix added to their number. Tropical depressions that enter or form in the Philippine area of responsibility are assigned a name by the Philippine Atmospheric and this can often result in the same storm having two names. 34 tropical depressions formed this year in the Western Pacific, of which 23 became tropical storms,13 storms reached typhoon intensity, of which 2 reached super typhoon strength. Large Super Typhoon Viola, which formed on July 22 east of the Philippines and it continued to the northwest, and weakened due to lack of inflow. Viola hit southeastern China as a typhoon on the 28th. The typhoon caused more than 1000 deaths in and around Shantou, Guangdong, China, on September 19, Tropical Depression 14W formed over the open Western Pacific. It tracked almost due westward, becoming a storm on the 20th. Elsie continued to intensify, and reached a peak of 175 mph winds on the 24th, after peaking, the typhoon steadily weakened as it moved westward. On the 26th 105 mph Typhoon Elsie hit northern Taiwan, after drifting northward, Elsie dissipated over China on September 28. The typhoon killed 102 people, with 24 missing and 227 injured from the system, just days after Elsie hit Taiwan, Tropical Storm Flossie approached Taiwan. From October 1 to the 5th, it drifted northward offshore of the island and it accelerated to the northeast, and became extratropical on the 10th east of Japan. Flossies heavy rains left 75 people dead, Western North Pacific tropical cyclones were named by the Joint Typhoon Warning Center. The first storm of 1969 was named Phyllis and the one was named Marie. Japan Meteorological Agency Joint Typhoon Warning Center
8.
1970 Pacific typhoon season
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The 1970 Pacific typhoon season has no official bounds, it ran year-round in 1970, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean, the scope of this article is limited to the Pacific Ocean, north of the equator and west of the international date line. Storms that form east of the line and north of the equator are called hurricanes. Tropical Storms formed in the entire west Pacific basin were assigned a name by the Joint Typhoon Warning Center, Tropical depressions in this basin have the W suffix added to their number. Tropical depressions that enter or form in the Philippine area of responsibility are assigned a name by the Philippine Atmospheric and this can often result in the same storm having two names. 27 tropical depressions formed this year in the Western Pacific, of which 24 became tropical storms,12 storms reached typhoon intensity, of which 7 reached super typhoon strength. Nancy originated from the interaction between an active ITCZ and a front near the Caroline Islands and the equator in mid February. An increase in convection was shown by weather satellites on February 18, the depression moved west, suppressed south by a high pressure ridge to the north, and gradually strengthened into a tropical storm and was given the name Nancy early on February 20. Nancy became a typhoon on the 22 about 100 miles northwest from Woleai, on February 23 Nancy passed to the north of Yap where strong gale winds occurred. Continuing to encounter more favorable conditions Nancy was able to achieve a peak intensity of 140 mph and this was the equivalent of a category four hurricane. It is rare to have a typhoon of this magnitude during the month of February, as noted by the JTWC, only Irma of the 1953 season reached the same intensity at the time. As Nancy approached the Philippine Islands the typhoon traversed to the ambit of the ridge that had kept it to the south. During the 25 Nancy passed east off the coast of the easternmost islands of the Philippines, on the island of Catanduanes, the edge of the eye brushed the eastern coast. A U. S. Coast Guard loran station on Catanduanes recorded intense winds, the storm encountered a hostile environment to the northeast of Luzon and began to weaken. By February 26 Nancy had become a storm and shortly afterward had transitioned into an extra tropical cyclone. By the 28 what remained of Nancy was a frontal trough, Nancy caused significant damage to the Philippines and surrounding islands. Particularly hard hit were the islands of Catanduanes and Samar, damage was estimated near a million dollars with 5,000 families homeless. On the Island of Yap heavy storm surge caused $160,000 in damages, a 6,065 ton American ship, Antinous, encountered the full brunt of the typhoon shortly before midnight, February 24
9.
International Date Line
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The International Date Line is an imaginary line of navigation on the surface of the Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. It passes through the middle of the Pacific Ocean, roughly following the 180° line of longitude but deviating to pass around some territories and this description is based on the most common understanding of the de facto International Date Line. See § De facto and de jure date lines below, the IDL is roughly based on the meridian of 180° longitude, roughly down the middle of the Pacific Ocean, and halfway around the world from the Greenwich meridian. In many places, the IDL follows the 180° meridian exactly, in other places, however, the IDL deviates east or west away from that meridian. These various deviations generally accommodate the political and/or economic affiliations of the affected areas, proceeding from north to south, the first deviation of the IDL from 180° is to pass to the east of Wrangel Island and the Chukchi Peninsula, the easternmost part of Russian Siberia. It then passes through the Bering Strait between the Diomede Islands at a distance of 1.5 kilometres from each island at 168°5837 W and it then bends considerably west of 180°, passing west of St. Lawrence Island and St. Matthew Island. The IDL crosses between the U. S. Aleutian Islands and the Commander Islands, which belong to Russia and it then bends southeast again to return to 180°. Thus, all of Russia is to the west of the IDL, and all of the United States is to the east except for the areas of Guam, the Northern Mariana Islands. The IDL remains on the 180° meridian until passing the equator, two US-owned uninhabited atolls, Howland Island and Baker Island, just north of the equator in the central Pacific Ocean, have the latest time on Earth. The IDL circumscribes Kiribati by swinging far to the east, almost reaching the 150°W meridian, kiribatis easternmost islands, the southern Line Islands south of Hawaii, have the most advanced time on Earth, UTC+14 hours. South of Kiribati, the IDL returns westwards but remains east of 180°, in much of this area, the IDL follows the 165°W meridian. Accordingly, Samoa, Tokelau, Wallis and Futuna, Fiji, Tonga, Tuvalu and New Zealands Kermadec Islands, American Samoa, the Cook Islands, Niue, and French Polynesia are east of the IDL and one day behind. The IDL then bends southwest to return to 180° and it follows that meridian until reaching Antarctica, which has multiple time zones. Conventionally, the IDL is not drawn into Antarctica on most maps, in contrast, a west-to-east circumnavigation of the globe loses an hour for every 15° of longitude crossed but gains back a day when crossing the IDL. The IDL must therefore be observed in conjunction with the Earths time zones, on crossing it in either direction, the calendar date is adjusted by one day. For the two hours between 10,00 and 11,59 UTC each day, three different calendar dates are observed at the time in different places on Earth. For example, at 10,15 UTC Thursday, it is 23,15 Wednesday in American Samoa, Thursday in most of the world, during the first hour, all three calendar dates include inhabited places. During the second one of the calendar dates is limited to an uninhabited maritime time zone twelve hours behind UTC
