Jet streams are narrow bands of strong winds in the upper troposphere and have dominant influences over short-term weather patterns, and long-term climate and global temperatures. The Jet Stream Visualization Tool (jsviz) is a graphical tool to help see the variable path of the strongest wind speeds in the upper atmosphere and how these maximum winds evolve with time and space. Combined with data layers of geopotential height and surface pressure, the tool helps provide understanding of the basic atmospheric dynamics associated with the jet stream. The tool is also used for evaluating the algo

jet streams. These are narrow, fast moving bands that flow from west to east and typically form at an elevation of around 9,100 m (30,000 ft). Jet streams The atmosphere of Earth consists of a layer of mixed gas (commonly referred to as air) that is retained by gravity, surrounding the Earth's surface. It contains variable quantities of suspended aerosols and particulates that create weather features such as clouds and hazes. The atmosphere serves as a protective buffer between the Earth's surface and outer space. It shields the surface from most me Th… Atmospheric circulation is the large-scale movement of air through the troposphere, and the means (with ocean circulation) by which heat is distributed around Earth. The large-scale structure of the atmospheric circulation varies from year to year, but the basic structure remains fairly constant because it is determined by Earth's rotation rate and the difference in solar radiation between the equator and poles. The axial tilt of the planet means the location of maximum heat is continually changing, resulting in seasonal variations. The uneven distribution of land and water further breaks up the flow of air. The flow of air around the planet is divided into three main convection cells by latitude. Around the equator, the Hadley cell is driven by the rising flow of air along the equator. In the upper atmosphere, this air flows toward the poles. At mid latitudes, this circulation is reversed, with ground air flowing toward the poles with the Ferrel cell. Finally, in the high latitudes is the Polar cell, where air again rises and flows toward the poles. The interface between these cells is responsible for jet streams. These are narrow, fast moving bands that flow from west to east and typically form at an elevation of around 9,100 m (30,000 ft). Jet streams can shift around depending on conditions. They are strongest in winter, when the boundaries between hot and cold air are the most pronounced. In the middle latitu The stratosphere is the second-lowest layer of Earth's atmosphere. It lies above the troposphere and is separated from it by the tropopause. This layer extends from the top of the troposphere at roughly 12 km (7.5 mi) above Earth's surface to the stratopause at an altitude of about 50 to 55 km (31 to 34 mi). 99% of the total mass of the atmosphere lies below 30 km (19 mi), and the atmospheric pressure at the top of the stratosphere is roughly 1/1000 the pressure at sea level. It contains the ozone layer, which is the part of Earth's atmosphere that contains relatively high concentrations of that gas. The stratosphere defines a layer in which temperatures rise with increasing altitude. This rise in temperature is caused by the absorption of ultraviolet radiation (UV) from the Sun by the ozone layer, which restricts turbulence and mixing. Although the temperature may be −80 °C (−110 °F; 190 K) at the tropopause, the top of the stratosphere is much warmer, and may be just below 0 °C. This layer is unique to the Earth; neither Mars nor Venus have a stratosphere because of low abundances of oxygen in their atmospheres. The stratospheric temperature profile creates very stable atmospheric conditions, so the stratosphere lacks the weather-producing air turbulence that is so prevalent in the troposphere. Consequently, the stratosphere is almost completely free of clouds and other forms of weather. However, polar stratospheric or nacreous clouds are occasionally seen in the lower part of this layer of the atmosphere where the air is coldest. The stratosphere is the highest layer that can be accessed by jet-powered aircraft. Different molecules absorb different wavelengths of radiation. For example, O2 and O3 absorb almost all radiation with wavelengths shorter than 300 nanometres. Water (H2O) absorbs at many wavelengths above 700 nm. When a molecule absorbs a photon, it increases the energy of the molecule. This heats the atmosphere, but the Atmospheric circulation is the large-scale movement of air through the troposphere, and the means (with ocean circulation) by which heat is distributed around Earth. The large-scale structure of the atmospheric circulation varies from year to year, but the basic structure remains fairly constant because it is determined by Earth's rotation rate and the difference in solar radiation between the equator and poles. The axial tilt of the planet means the location of maximum heat is continually changing, resulting in seasonal variations. The uneven distribution of land and water further breaks up the flow of air. The flow of air around the planet is divided into three main convection cells by latitude. Around the equator, the Hadley cell is driven by the rising flow of air along the equator. In the upper atmosphere, this air flows toward the poles. At mid latitudes, this circulation is reversed, with ground air flowing toward the poles with the Ferrel cell. Finally, in the high latitudes is the Polar cell, where air again rises and flows toward the poles. The interface between these cells is responsible for jet streams. These are narrow, fast moving bands that flow from west to east and typically form at an elevation of around 9,100 m (30,000 ft). Jet streams can shift around depending on conditions. They are strongest in winter, when the boundaries between hot and cold air are the most pronounced. In the middle latitudes, it is instabilities in the jet streams that are responsible for moving weather systems. As with the oceans, the Earth's atmosphere is subject to waves and tidal forces. These are triggered by non-uniform heating by the Sun, and by the daily solar cycle, respectively. Wave-like behavior can occur on a variety of scales, from smaller gravity waves that transfer momentum into the higher atmospheric layers, to much larger planetary waves, or Rossby waves. Atmospheric tides are periodic oscillations of the troposphere and stratosphere that transport energy to the upper atmosphere.

west to east. The Northern and Southern Hemispheres each have a predictable though discontinuous polar jet and subtropical jet; low-level jets and other This glossary of meteorology is a list of terms and concepts relevant to meteorology and atmospheric science, their sub-disciplines, and related fields. jet stream Also simply jet. A narrow, fast-flowing, meandering air current primarily occurring in the upper part of the troposphere, at altitudes above 9 km (30,000 ft), and… Buys Ballot's law A meteorological heuristic derived from the general observation that, in the Northern Hemisphere, if an observer stands with their back to the wind (i.e. facing the direction toward which the wind is blowing), atmospheric pressure is lower on the observer's left and higher on the observer's right. This is because air moves counterclockwise around low-pressure centers in the Northern Hemisphere, a consequence of the Coriolis force; the phenomenon is reversed in the Southern Hemisphere. The rule holds approximately true at high latitudes, where the angle between the wind direction and the pressure gradient force is generally nearly perpendicular, but is less reliable or even absent at low latitudes. climatology Also climate science. A branch of the atmospheric sciences that studies climate, defined as weather conditions averaged over an extended to indefinite period of time. Climatology incorporates aspects of oceanography, geology, biogeochemistry, and the related field of meteorology to understand the long-term dynamics of climate-influencing phenomena and to produce climate models which can be used to estimate past climates and predict future climates. ensemble forecasting A weather forecasting technique in which a numerical weather model generates a set of multiple (often several dozen) forecasts, each based on a slightly different set of initial atmospheric conditions, intended to provide an indication of the range of possible future states of the atmosphere. If the forecasts are consistent, they are usually considered reliable; if they diverge, meteorologists may feel less confident in making specific predictions for the forecast area. hydrosphere The combined mass of all solid, liquid, and gaseous forms of water found on, beneath, or above the surface of the Earth, including all oceans, lakes, streams, groundwater, atmospheric water vapor, snow, ice caps, and glaciers. jet stream Also simply jet. A narrow, fast-flowing, meandering air current primarily occurring in the upper part of the troposphere, at altitudes above 9 km (30,000 ft), and usually flowing from west to east. The Northern and Southern Hemispheres each have a predictable though discontinuous polar jet and subtropical jet; low-level jets and other types of jet streams can form under certain conditions. jet streak Also jet stream core or jet maximum. The region of maximum wind speed that runs along the elongated axis of a jet stream. In the local winter, the maximum speed in the polar-front jet stream can reach upwards of 200 knots (370 km/h; 230 mph). lake-effect snow A weather phenomenon produced when a cold air mass moves across long expanses of warmer lake water, which causes the lowest layers of air to pick up warm water vapor from the lake, rise through the upper layers, freeze and then precipitate on the lake's leeward shores. In combination with orographic lift, the effect produces narrow but very intense bands of precipitation, especially snow, which can deposit at very high rates and result in very large amounts of snowfall over a region. The same effect can also occur over bodies of salt water, when it is termed ocean-effect or bay-effect snow. lee trough Also lee depression, orographic depression, and dynamic trough. A trough of low atmospheric pressure that forms preferentially to the lee or downwind side of a mountain barrier when air currents flow in directions perpendicular to the barrier and become vertically "squashed" as they cross it. As the column resumes its original depth on the other side of the barrier, it tends to develop a strong spin about its vertical axis, which manifests as a low-pressure center. obscuring phenomena Any atmospheric phenomenon exclusive of clouds that restricts vertical visibility, including various hydrometeors such as rain and snow as well as lithometeors such as dust and sand. polar vortex Either of the two very large, persistent, rotating, upper-level low-pressure areas suspended in the Earth's atmosphere near the geographic poles. The polar vortices predictably strengthen during their local winter and weaken during their local summer as the temperature contrast between the poles and the Equator changes. When either vortex is weak, high-pressure zones of lower latitudes may push poleward, driving the vortex, jet stream, and masses of cold, dry polar air into the mid-latitudes, which can cause sudden, dramatic drops in temperature known as cold waves. quasi-geostrophic theory A theory of atmospheric dynamics that involves the quasi-geostrophic approximation in the derivation of the quasi-geostrophic equations. This theory is relatively accurate for synoptic-scale atmospheric motions in which the Rossby number is less than unity, but it cannot accurately describe some local atmospheric structures such as fronts or small, strong low-pressure cells as well as other theories. tropical cyclone Variously hurricane, typhoon, tropical storm, cyclonic storm, or simply cyclone. A very large, rapidly rotating storm system characterized by a low-pressure center surrounded by a closed low-level atmospheric circulation, strong winds, and continuous spiral bands of thunderstorms that produce heavy rain. Tropical cyclones develop almost exclusively over and derive their strength from warm tropical seas. The strongest systems can last for more than a week, span more than 1,600 km (1,000 mi) in diameter, and cause significant damage to coastal regions with powerful winds, storm surges,

Intended as a supplement to undergraduate college geography courses, this resource paper reviews the mechanism by which surface weather features are linked with the mid-atmospheric circulation within the westerly wind belt. Specifically, vertical atmospheric motions associated with certain aspects of the upper tropospheric flow, including jet streams, are discussed. Processes at this level are related to such surface weather features as cyclones, anticyclones, and air masses, and the way these are modified and steered across the country. The evolution of monthly flow patterns during the period

A review of papers related to jet streams in the Southern Hemisphere is presented. The structural features of jet streams and an analysis of their variability during different periods of the 20th and early 21st centuries are discussed. The results of climate modeling of jet streams within the CMIP and PAMIP projects are described. Potential causes for changes in the position and intensity of jet streams on both long and short timescales are identified. Опис аны р езу ль та ты работ , связанных с климатическим моделированием струйных течений в рамк ах про- екто в CMIP и PA M I P . У к азаны возможные причины изменения поло жения и интен- сивно сти ст руйных течений как на длинных, т ак и на к о ротких временных масшта- бах. Ключевы е сл ова: струйные течения, Южно е полушарие, реан ализ, Ю жная к оль- цевая мо да, изменение климата, стр ат о сферный озо н, в у лканиче ские извержения Southern Hemisphere jet streams and factors determini ng their dynamics A.R. Ivanova Hydr omete orologic al Re sear ch Ce nter of Russ ian Feder ation, M oscow , Rus sia ivanova @mecom. ru A revi ew of pap ers related to jet streams in the So uthern Hemisphere is present ed. The structural fe atures of jet s treams and an analys is of their varia bility during dif ferent periods of the 20th an d earl y 21st c entur ies a re dis cusse d. T he res ults of clima te modeling of jet streams with in the CMIP and P AMIP projects are descr ibed. Potential cau ses for changes in the posit ion an d inte nsity of jet st ream s on bot h long and s hort t ime sca les are identif ied. P. 559 - 617. 22. G allego D., Ri bera P., Garcia - Herrera R., Herna ndez E., Gimen o L. A new look for the Southe rn Hem isphere je t stre am // Cl imat e Dynam ics. 2005. Vol. 24. P. 6 0 7- 621. DOI : 10.10 07/s00 382 - 005 - 0006 - 7 23. G ibbs W.J . Notes on the mean jet - stream over A ustra lia // J ourn al of Meteor ology . 1952. Vol. 9. P. 2 79 - 284. 24. Gu est P.J. 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