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jet stream

 
Dictionary: jet stream
 

n.
  1. A high-speed, meandering wind current, generally moving from a westerly direction at speeds often exceeding 400 kilometers (250 miles) per hour at altitudes of 15 to 25 kilometers (10 to 15 miles).
  2. A high-speed stream; a jet.

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A relatively narrow, fast-moving wind current flanked by more slowly moving currents. Jet streams are observed principally in the zone of prevailing westerlies above the lower troposphere and in most cases reach maximum intensity, with regard both to speed and to concentration, near the tropopause. At a given time, the position and intensity of the jet stream may significantly influence aircraft operations because of the great speed of the wind at the jet core and the rapid spatial variation of wind speed in its vicinity. Lying in the zone of maximum temperature contrast between cold air masses to the north and warm air masses to the south, the position of the jet stream on a given day usually coincides in part with the regions of greatest storminess in the lower troposphere, though portions of the jet stream occur over regions which are entirely devoid of cloud. The jet stream is often called the polar jet, because of the importance of cold, polar air. The subtropical jet is not associated with surface temperature contrasts, like the polar jet. Maxima in wind speed within the jet stream are called jet streaks. See also Atmospheric general circulation.


 
US Military Dictionary: jet stream
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A narrow band of high-velocity wind in the upper troposphere or in the stratosphere.

See the Introduction, Abbreviations and Pronunciation for further details.

 
Geography Dictionary: jet stream
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The name given to any narrow belt of strong, upper-atmosphere winds, blowing at speeds of over 45 m s-1, between 7.5 and 14 km above the earth's surface. Jet streams are several hundred kilometres wide and 2-4 km deep, owing their existence to the conservation of angular momentum, and appearing as a fast-moving track inside lighter winds. Such is their strength that aircraft routes which run counter to jet movements are generally avoided. Jets are coincident with major breaks in the tropopause.

The polar-front jet stream is a frontal wind, located just below the tropopause, blowing parallel to the surface fronts, moving with them, and draining the air rising from the fronts. It is strongest at the 200-300 mb level, and swings between latitudes 40 and 60 °N, since it is located along the Rossby troughs, so that speed and location vary from day to day with the Rossby waves. It is not necessarily continuous. This jet is coincident with strong horizontal shifts in temperature and pressure (see baroclinic) since it marks the polar front; the boundary between cold polar air and warm tropical air, where the steepness of the isotherms is at a maximum. It has important effects on convergence and divergence in the upper air. For example, at the ‘jet entrance’, the pressure gradient steepens, and the wind becomes super- geostrophic, leading to high-level convergence. A strong polar-front jet is associated with rapidly moving depressions; a weak jet with a blocking pattern where northerly and southerly air streams dominate.

The westerly subtropical jet is at the poleward limit of the Hadley cell, around 30° N and S; the northern subtropical jet is strongest at the 200 mb level, and above the Indian subcontinent. This is one of the most powerful wind systems on earth, at times reaching speeds of 135 m s-1, and it follows a more fixed pattern than the polar-front jet. It results from the poleward drift of air in the Hadley circulation and the conservation of angular momentum. Some anticyclones develop beneath the westerly subtropical jet, through high-level convergence and subsidence, but the subtropical, westerly jets do not seem to affect surface weather as much as the polar-front jets do.

The tropical, easterly jet develops during the summer months at 15° N, and is strongest at the time of the summer monsoon.

The stratospheric, subpolar jet stream blows at a height of 30 000 metres, being westerly in winter and easterly in summer. See conservation of angular momentum.

 

Any of several long, narrow, high-speed air currents that flow eastward in a generally horizontal zone in the stratosphere or upper troposphere. Jet streams are characterized by wind motions that generate strong vertical shearing action, considered largely responsible for the clear-air turbulence experienced by aircraft. They also have an effect on weather patterns. Jet streams circle the Earth in meandering paths, shifting position as well as speed with the seasons. In the winter they are nearer the Equator and their speeds are higher than in the summer. There are often two, sometimes three, jet-stream systems in each hemisphere.

For more information on jet stream, visit Britannica.com.

 
Columbia Encyclopedia: jet stream
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jet stream, narrow, swift currents or tubes of air found at heights ranging from 7 to 8 mi (11.3–12.9 km) above the surface of the earth. They are caused by great temperature differences between adjacent air masses. There are four major jet streams. Although discontinuous at some points, they circle the globe at middle and polar latitudes, both in each hemisphere. The mean position of the stream in the Northern Hemisphere is between lat. 20 and 50 degrees N; the polar stream is between lat 30 and 70 degrees N. Wind speeds average 35 mi (56.3 km) per hr in summer and 75 mi (120.7 km) per hr in winter, although speeds as high as 200 mi (321.9 km) per hr have been recorded. Instead of moving along a straight line, the jet stream flows in a wavelike fashion; the waves propagate eastward (in the Northern Hemisphere) at speeds considerably slower than the wind speed itself. Since the progress of an airplane is aided or impeded depending on whether tail winds or head winds are encountered, in the Northern Hemisphere the jet stream is sought by eastbound aircraft, in order to gain speed and save fuel, and avoided by westbound aircraft.


 
Science Dictionary: jet stream
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A narrow band of swiftly moving air found at very high altitudes.

  • Movements of the jet stream have important (but generally short-lived) effects on weather patterns.
  • Travel time in an airplane can be lengthened or shortened by the jet stream, depending on the direction of flight and the strength of the stream.
  •  
    Military Dictionary: jet stream
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    (DOD) A narrow band of high velocity wind in the upper troposphere or in the stratosphere.

     
    Wikipedia: Jet stream
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    Jet streams flow from west to east in the upper portion of the troposphere.

    Jet streams, or just jets in context, are fast flowing, narrow air currents found in the atmosphere of planets at the tropopause, the transition between the troposphere (where temperature decreases with height) and the stratosphere (where temperature increases with height).[1] They are thought to be caused by a combination of atmospheric heating (by solar radiation and/or internal heat) and a planet's rotation on its own axis. On Earth, the strongest jet streams are the polar jets (7-12 km or 23,000-39,000 ft above sea level) and the higher and somewhat weaker subtropical jets (10-16 km or 33,000-52,000 ft). The northern hemisphere and the southern hemisphere each have both a polar jet and a subtropical jet. The singular term "jet stream" is often used to describe Earth's northern hemisphere polar jet, since it is the most important one for meteorology and aviation as it covers much of North America, Europe, and Asia, especially in winter, while the southern hemisphere polar jet mostly circles Antarctica all year round.

    Jet streams form near boundaries of adjacent air masses with significant differences in temperature, such as the polar region and the warmer air to the south.[2] Jet streams are not continuous or circular around the perimeter of a planet: they may start, stop, split into two or more parts, combine into one stream, or flow in various directions including the opposite direction of most of the jet. The path of a jet stream typically has a meandering shape, and these meanders are one manifestation of Rossby waves. Rossby waves propagate westward with respect to the flow in which they are embedded, which translates to a slower eastward migration across the globe than smaller scale short wave troughs. The major jet streams are westerly winds (flowing west to east). During the northern hemisphere summer, easterly jets can form in tropical regions, typically in a region where dry air encounters more humid air at high altitudes. Low level jets can form wherever low level winds are squeezed.

    Meteorologists use the location of the jet streams as an aid in weather forecasting. The main commercial use of the jet streams is in air travel, as flight time can be dramatically affected by either flying with or against a stream. One type of clear-air turbulence is found in a jet stream's vicinity, which can be a hazard to aircraft. One future benefit of jet streams could be to power airborne wind turbines.

    Contents

    Discovery

    Jet streams may have been first detected in the 1920s by Japanese meteorologist Wasaburo Ooishi.[3] From a site near Mount Fuji, he tracked pilot balloons, also known as pibals (balloons used to determine upper level winds using a theodolite and the balloon's known ascension rate due to its internal gas),[4] as they rose into the atmosphere. Ooishi's work largely went unnoticed outside of Japan. American pilot Wiley Post, the first man to fly around the world solo in 1933, is often given some credit for discovery of jet streams. Post invented a pressurized suit that let him fly above 6,200 metres (20,000 ft). In the year before his death, Post made several attempts at a high-altitude transcontinental flight, and noticed that at times his ground speed greatly exceeded his air speed.[5] German meteorologist H. Seilkopf is credited with coining the term "jet stream" (Strahlströmung) in a 1939 paper.[6] Many sources credit real understanding of the nature of jet streams to regular and repeated flight-path traversals during World War II. Flyers consistently noticed tailwinds in excess of 100 mph in flights, for example, between the US and UK.[7]

    Description

    Cross section of the subtropical and polar jet streams by latitude

    Polar jet streams are typically located near the 250 hPa (7.38 inHg) pressure level, or 7 kilometres (4.3 mi) to 12 kilometres (7.5 mi) above sea level, while the weaker subtropical jet streams are much higher, between 10 kilometres (6.2 mi) and 16 kilometres (9.9 mi) above sea level. In each hemisphere, both upper-level jet streams form near breaks in the tropopause, which is at a higher altitude near the equator than it is over the poles, with large changes in its height occurring near the location of the jet stream.[8][9] The northern hemisphere polar jet stream is most commonly found between latitudes 30°N and 60°N, while the northern subtropical jet stream located close to latitude 30°N. The upper level jet stream is said to "follow the sun" as it moves northward during the warm season, or late spring and summer, and southward during the cold season, or autumn and winter.[10][11]

    Jet streams are typically continuous over long distances, but discontinuities are common.[12] The path of the jet typically has a meandering shape, and these meanders themselves propagate east, at lower speeds than that of the actual wind within the flow. Each large meander, or wave, within the jet stream is known as a Rossby wave. Rossby waves are caused by changes in the Coriolis effect with latitude, and propagate westward with respect to the flow in which they are embedded, which slows down the eastward migration of upper level troughs and ridges across the globe when compared to their embedded shortwave troughs.[13] Shortwave troughs are smaller packets of upper level energy, on the scale of 1,000 kilometres (620 mi) to 4,000 kilometres (2,500 mi) long,[14] which move through the flow pattern around large scale, or longwave, ridges and troughs within Rossby waves.[15] Jet streams can split into two due to the formation of an upper-level closed low, which diverts a portion of the jet stream under its base, while the remainder of the jet moves by to its north.

    The wind speeds vary according to the temperature gradient, exceeding 92 kilometres per hour (50 kn),[12] although speeds of over 398 kilometres per hour (215 kn) have been measured.[16] Meteorologists now understand that the path of jet streams steers cyclonic storm systems at lower levels in the atmosphere, and so knowledge of their course has become an important part of weather forecasting. For example, in 2007, Britain experienced severe flooding as a result of the polar jet staying south for the summer.[17][18]

    Cause

    Upper-level variety

    General configuration of the polar and subtropical jet streams

    In general, winds are strongest just under the tropopause (except during tornadoes, hurricanes or other anomalous situations). If two air masses of different temperatures or densities meet, the resulting pressure difference caused by the density difference (which causes wind) is highest within the transition zone. The wind does not flow directly from the hot to the cold area, but is deflected by the Coriolis effect and flows along the boundary of the two air masses.[19] The polar front and subtropical jets merge at some locations and times, while at other times they are well separated.

    All these facts are consequences of the thermal wind relation. The balance of forces on an atmospheric parcel in the vertical direction is primarily between the pressure gradient and the force of gravity, a balance referred to as hydrostatic. In the horizontal, the dominant balance outside of the tropics is between the Coriolis effect and the pressure gradient, a balance referred to as geostrophic. Given both hydrostatic and geostrophic balance, one can derive the thermal wind relation: the vertical derivative of the horizontal wind is proportional to the horizontal temperature gradient. The sense of the relation is such that temperatures decreasing polewards implies that winds develop a larger eastward component as one moves upwards. Therefore, the strong eastward moving jet streams are in part a simple consequence of the fact that the equator is warmer than the north and south poles.[19]

    The thermal wind relation does not immediately provide an explanation for why the winds are organized in tight jets, rather than distributed more broadly over the hemisphere. There are two factors that contribute to this sharpness of the jets. One is the tendency for developing cyclonic disturbances in midlatitudes to form fronts. A front is a sharp localized gradient in temperature. The polar front jet stream can be thought of as the result of this frontogenesis process in midlatitudes, as the storms concentrate the north-south temperature contrast into relatively narrow regions.[12]

    An alternative explanation is more appropriate for the subtropical jet, which forms at the poleward limit of the tropical Hadley cell. One can visualize this circulation as being symmetric with respect to longitude. Rings of air encircling the Earth move polewards beneath the tropopause from the equator into the subtropics. As they do so they tend to conserve their angular momentum. But they are also moving closer to the axis of rotation, so they must spin faster in the direction of rotation, implying an increased eastward component of the winds.[20]

    Jupiter's atmosphere has multiple jet streams, forming the familiar banded color structure, caused by internal heating.[16] The factors that control the number of jet streams in a planetary atmosphere is an active area of research in dynamical meteorology. In models, as one increases the planetary radius, holding all other parameters fixed, the number of jet streams increases.

    Other jets

    There are wind maxima in the atmosphere at other levels of the atmosphere that are referred to as jets, including the mid-level African easterly jet which occurs during the Northern Hemisphere summer between 10°N and 20°N above West Africa, and the nocturnal poleward low-level jet in the Great Plains.[21] The low-level easterly African jet stream is considered to play a crucial role in the southwest monsoon of Africa,[22] and helps form the tropical waves which march across the tropical Atlantic and eastern Pacific oceans during the warm season.[23] The formation of the thermal low over northern Africa leads to a low-level westerly jet stream from June into October.[24]

    A barrier jet in the low levels forms just upstream of mountain chains, with the mountains forcing the jet to be oriented parallel to the mountains. The mountain barrier increases the strength of the low level wind by 45 percent.[25] A southerly low-level jet in the Great Plains helps fuel overnight thunderstorm activity during the warm season, normally in the form of mesoscale convective systems which form during the overnight hours.[26] A similar phenomenon develops across Australia, which pulls moisture poleward from the Coral Sea towards cut-off lows which form mainly across southwestern portions of the continent.[27]

    Uses

    Aviation

    Flights between Tokyo and Los Angeles using the jet stream eastbound and a great circle route westbound.

    The location of the jet stream is extremely important for aviation. Commercial use of the jet stream began on November 18, 1952, when Pan Am flew from Tokyo to Honolulu at an altitude of 7,600 metres (25,000 ft). It cut the trip time by over one-third, from 18 to 11.5 hours.[28] Not only does it cut time off the flight, it also nets fuel savings for the airline industry.[29] Within North America, the time needed to fly east across the continent can be decreased by about 30 minutes if an airplane can fly with the jet stream, or increased by more than that amount if it must fly west against it.

    Associated with jet streams is a phenomenon known as clear air turbulence (CAT), caused by vertical and horizontal windshear connected to the jet streams.[30] The CAT is strongest on the cold air side of the jet,[31] next to and just underneath the axis of the jet.[32] Clear air turbulence can be hazardous to aircraft, and has caused fatal accidents, such as United Airlines Flight 826.[33][34]

    Future power generation

    Scientists are investigating ways to harness the wind energy within the jet stream using airborne wind turbines. Kite-like wind generators have been proposed, which would transmit electricity back to the ground via either aluminium cables, copper cables, or beams of microwave energy. Tethered balloons, which reach heights of 4,500 metres (15,000 ft), have been used to monitor drug trafficking over many years, with no reported airplane incidents until April 21, 2007 when three individuals were killed in the Florida Keys when their Cessna 182 struck a steel cable tethered to a large unpiloted government radar surveillance blimp (aerostat) over Cudjoe Key.[35][36] According to one estimate, only 1 percent of the potential wind energy in the jet stream could meet the world's current energy needs. The required technology would reportedly take 10–20 years to develop.[37]

    Unpowered aerial attack

    Changes due to climate cycles

    Effects of ENSO

    Impact of El Niño and La Niña on North America

    The changing of the normal location of upper-level jet streams can be anticipated during phases of the El Niño-Southern Oscillation (ENSO), which leads to consequences precipitation-wise and temperature-wise across North America, affects tropical cyclone development across the eastern Pacific and Atlantic basins. Combined with the Pacific Decadal Oscillation, ENSO can also impact cold season rainfall in Europe.[38] Changes in ENSO also change the location of the jet stream over South America, which partially effects precipitation distribution over the continent.[39]

    El Niño

    During El Niño events, increased precipitation is expected in California due to a more southerly, zonal, storm track.[40] During the El Niño portion of ENSO, increased precipitation falls along the Gulf coast and Southeast due to a stronger than normal, and more southerly, polar jet stream.[41] Snowfall is greater than average across the southern Rockies and Sierra Nevada mountain range, and is well-below normal across the Upper Midwest and Great Lakes states.[42] The northern tier of the lower 48 exhibits above normal temperatures during the fall and winter, while the Gulf coast experiences below normal temperatures during the winter season.[43][44] The subtropical jet stream across the deep tropics of the Northern Hemisphere is enhanced due to increased convection in the equatorial Pacific, which decreases tropical cyclogenesis within the Atlantic tropics below what is normal, and increases tropical cyclone activity across the eastern Pacific.[45] In the Southern Hemisphere, the subtropical jet stream is displaced equatorward, or north, of its normal position, which diverts frontal systems and thunderstorm complexes from reaching central portions of the continent.[39]

    La Niña

    Across North America during La Niña, increased precipitation is diverted into the Pacific Northwest due to a more northerly storm track and jet stream.[46] The storm track shifts far enough northward to bring wetter than normal conditions (in the form of increased snowfall) to the Midwestern states, as well as hot and dry summers.[47][48] Snowfall is above normal across the Pacific Northwest and western Great Lakes.[49] Across the North Atlantic, the jet stream is stronger than normal, which directs stronger systems with increased precipitation towards Europe.[50]

    Jetstreams possibly moving

    Between 1979 and 2001, it has been found that the position of the jet stream has been moving northward at a rate of 2.01 kilometres (1.25 mi) per year across the Northern Hemisphere. Across North America, this type of change could lead to drier conditions across the southern tier of the United States and more frequent and more intense tropical cyclones in the tropics. A similar slow poleward drift was found when studying the Southern Hemisphere jet stream over the same time frame.[51]

    The Dust Bowl

    Evidence suggests the jet stream was at least partially responsible for the wide drought conditions during the 1930s Dust Bowl in the Midwest United States. Normally, the jet stream flows east over the Gulf of Mexico and turns northward pulling up moisture and dumping rain onto the Great Plains. During the Dust Bowl, the jet stream weakened and changed course traveling farther south than normal. This starved the Great Plains and other areas of the Midwest of precious rain creating dusty conditions.[52]

    See also

    References

    1. ^ United States Department of Energy June 26, 2002. Ask a Scientist. Retrieved on 2008-05-05.
    2. ^ University of Illinois. Jet Stream. Retrieved on 2008-05-04.
    3. ^ John M. Lewis. Ooishi's Observation: Viewed in the Context of Jet Stream Discovery. Retrieved on 2008-05-08.
    4. ^ Martin Brenner. Pilot Balloon Resources. Retrieved on 2008-05-13.
    5. ^ Acepilots.com. Wiley Post. Retrieved on 2008-05-08.
    6. ^ John M. Lewis: Clarifying the Dynamics of the General Circulation: Phillips’s 1956 Experiment from: Bulletin of the American Meterological Society, Vol. 79, No. 1, January 1988
    7. ^ BBC. Weather Basics - Jet Streams. Retrieved on 2008-05-08.
    8. ^ David R. Cook Jet Stream Behavior. Retrieved on 2008-05-08.
    9. ^ B. Geerts and E. Linacre. The Height of the Tropopause. Retrieved on 2008-05-08.
    10. ^ National Weather Service JetStream. The Jet Stream. Retrieved on 2008-05-08.
    11. ^ McDougal Littell. Paths of Polar and Subtropical Jet Streams. Retrieved on 2008-05-13.
    12. ^ a b c Glossary of Meteorology. Jet Stream. Retrieved on 2008-05-08.
    13. ^ Glossary of Meteorology. Rossby Wave. Retrieved on 2008-05-13.
    14. ^ Glossary of Meteorology. Cyclone wave. Retrieved on 2008-05-13.
    15. ^ Glossary of Meteorology. Short wave. Retrieved on 2008-05-13.
    16. ^ a b Robert Roy Britt. The jet stream moves from West to East bringing hot and cold air. et Streams On Earth and Jupiter. Retrieved on 2008-05-04.
    17. ^ "Why has it been so wet?". BBC. July 23, 2007. http://news.bbc.co.uk/1/hi/magazine/6911918.stm. Retrieved on 2007-07-31. 
    18. ^ Blackburn, Mike; Hoskins, Brian; Slingo, Julia: "Notes on the Meteorological Context of the UK Flooding in June and July 2007" (PDF). Walker Institute for Climate System Research. July 25, 2007. http://www.walker-institute.ac.uk/news/summer_2007.pdf. Retrieved on 2007-08-29. 
    19. ^ a b John P. Stimac. Air pressure and wind. Retrieved on 2008-05-08.
    20. ^ Lyndon State College Meteorology. Jet Stream Formation - Subtropical Jet. Retrieved on 2008-05-08.
    21. ^ Dr. Alex DeCaria. Lesson 4 – Seasonal-mean Wind Fields. Retrieved on 2008-05-03.
    22. ^ Kerry H. Cook. Generation of the African Easterly Jet and Its Role in Determining West African Precipitation. Retrieved on 2008-05-08.
    23. ^ Chris Landsea. AOML Frequently Asked Questions. Subject: A4) What is an easterly wave ? Retrieved on 2008-05-08.
    24. ^ B. Pu and K. H. Cook (2008). Dynamics of the Low-Level Westerly Jet Over West Africa. American Geophysical Union, Fall Meeting 2008, abstract #A13A-0229. Retrieved on 2009-03-08.
    25. ^ J. D. Doyle. The influence of mesoscale orography on a coastal jet and rainband. Retrieved on 2008-12-25.
    26. ^ Matt Kumijan, Jeffry Evans, and Jared Guyer. The Relationship of the Great Plains Low-Level Jet to Nocturnal MCS Development. Retrieved on 2008-05-08.
    27. ^ L. Qi, L.M. Leslie, and S.X. Zhao. Cut-off low pressure systems over southern Australia: climatology and case study. Retrieved on 2008-05-08.
    28. ^ M. D. Klaas. Stratocruiser: Part three. Retrieved on 2008-05-08.
    29. ^ Ned Rozell. Amazing flying machines allow time travel. Retrieved on 2008-05-08.
    30. ^ BBC. Jet Streams in the UK. Retrieved on 2008-05-08.
    31. ^ M. P. de Villiers and J. van Heerden. Clear air turbulence over South Africa. Retrieved on 2008-05-08.
    32. ^ CLARK T. L., HALL W. D., KERR R. M., MIDDLETON D., RADKE L., RALPH F. M., NEIMAN P. J., LEVINSON D. Origins of aircraft-damaging clear-air turbulence during the December 9, 1992 Colorado downslope windstorm : Numerical simulations and comparison with observations. Retrieved on 2008-05-08.
    33. ^ National Transportation Safety Board. Aircraft Accident Investigation United Airlines flight 826, Pacific Ocean December 28, 1997. Retrieved on 2008-05-13.
    34. ^ Staff writer (December 29, 1997). "NTSB investigates United Airlines plunge". CNN. http://www.cnn.com/US/9712/29/united.turbulence/. Retrieved on 2008-05-13. 
    35. ^ Aero-News Network. Three Lost When C-182 Hits Blimp Cable Off FL CoastRetrieved on 2009-05-30
    36. ^ Monroe County Sheriff’s Office Daily Crime and Information Report, April 2007 Keys Plane crash victims identifiedRetrieved on 2009-05-30
    37. ^ Keay Davidson. Scientists look high in the sky for power. Retrieved on 2008-05-08.
    38. ^ Davide Zanchettin, Stewart W. Franks, Pietro Traverso, and Mario Tomasino. On ENSO impacts on European wintertime rainfalls and their modulation by the NAO and the Pacific multi-decadal variability described through the PDO index. Retrieved on 2008-05-13.
    39. ^ a b Caio Augusto dos Santos Coelho and Térico Ambrizzi. 5A.4. Climatological Studies of the Influences of El Niño Southern Oscillation Events in the Precipitation Pattern Over South America During Austral Summer. Retrieved on 2008-05-13.
    40. ^ John Monteverdi and Jan Null. WESTERN REGION TECHNICAL ATTACHMENT NO. 97-37 NOVEMBER 21, 1997: El Niño and California Precipitation. Retrieved on 2008-02-28.
    41. ^ Climate Prediction Center. El Niño (ENSO) Related Rainfall Patterns Over the Tropical Pacific. Retrieved on 2008-02-28.
    42. ^ Climate Prediction Center. ENSO Impacts on United States Winter Precipitation and Temperature. Retrieved on 2008-04-16.
    43. ^ Climate Prediction Center. Average October-December (3-month) Temperature Rankings During ENSO Events. Retrieved on 2008-04-16.
    44. ^ Climate Prediction Center. Average December-February (3-month) Temperature Rankings During ENSO Events. Retrieved on 2008-04-16.
    45. ^ "How do El Niño and La Nina influence the Atlantic and Pacific hurricane seasons?" (FAQ). Climate Prediction Center. http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/ensofaq.shtml#HURRICANES. Retrieved on 2008-03-21. 
    46. ^ Nathan Mantua. La Niña Impacts in the Pacific Northwest. Retrieved on 2008-02-29.
    47. ^ Southeast Climate Consortium. SECC Winter Climate Outlook. Retrieved on 2008-02-29.
    48. ^ Reuters. La Nina could mean dry summer in Midwest and Plains. Retrieved on 2008-02-29.
    49. ^ Climate Prediction Center. ENSO Impacts on United States Winter Precipitation and Temperature. Retrieved on 2008-04-16.
    50. ^ Paul Simons and Simon de Bruxelles. More rain and more floods as La Niña sweeps across the globe. Retrieved on 2008-05-13.
    51. ^ Associated Press. Jet stream found to be permanently drifting north. Retrieved on 2008-05-08.
    52. ^ Weather at About.com. Causes of the Dust Bowl in the United States. Retrieved on 2008-06-10.

    External links

    CRWS Jet stream analyses


     
     

     

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