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2019 tg atmosphere2 atmospheric circulation
The document discusses atmospheric circulation and weather systems. It explains that uneven heating of the Earth's surface causes pressure differences in the atmosphere which drive wind patterns. Key factors that determine winds include temperature, pressure, humidity, and the forces of pressure gradient, friction, and the Coriolis effect from the Earth's rotation. It describes global wind systems like the Hadley, Ferrel, and polar cells that comprise the general circulation. It also covers local winds, air masses, fronts, and storm systems like cyclones, thunderstorms, and tornadoes.
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2019 tg atmosphere2 atmospheric circulation
- 1. Atmosphere ATMOSPHERIC CIRCULATION AND WEATHERSYSTEMS Juan Antonio García González University of Castilla La Mancha Geographying in the clouds ; -) orcid.org/0000-0001-7049-1085
- 2. We live atthe bottom of a huge pile of air The amount of heat received by different parts of the earth is not the same
- 3. This variation causespressure differences in the atmosphere Air expands when heated and gets compressed when cooled
- 4. ELEMENTS OF WEATHERAND CLIMATE • Temperature • Pressure • Winds • Humidity Clouds And Precipitation
- 5. The weight ofa column of air contained in a unit area from the mean sea level to the top of the atmosphere is called the atmospheric pressure. The atmospheric pressure is expressed in units of mb. and Pascals. The widely used unit is kilo Pascal written as hPa. TORRICELLI'S EXPERIMENT
- 6. Due to gravitythe air at the surface is denser and hence has higher pressure In the lower atmosphere the pressure decreases rapidly with height The decrease amounts to about 1 mb for each 10 m increase in elevation The pressure decreases with height VERTICAL VARIATION OF PRESSURE
- 7. Near the equatorthe sea level pressure is low and the area is known as equatorial low. Along 30° N and 30o S are found the high-pressure areas known as the subtropical highs. Further pole wards along 60o N and 60o S, the low- pressure belts are termed as the sub polar lows. Near the poles the pressure is high and it is known as the polar high. HORIZONTAL DISTRIBUTION OF PRESSURE https://serc.carleton.edu/eslabs/weather/3b.html
- 8. HORIZONTAL DISTRIBUTION OFPRESSURE Horizontal distribution of pressure is studied by drawing isobars at constant levels. Isobars are lines connecting places having equal pressure. it is measured at any station after being reduced to sea level for purposes of comparison
- 9. Small differences inpressure are highly significant in terms of the wind direction and velocity • Low-pressure system is enclosed by one or more isobars with the lowest pressure in the centre • High-pressure system is also enclosed by one or more isobars with the highest pressure in the centre. https://www.keesfloor.nl/art/p-ww-ddff.htm
- 10. FORCES AFFECTING THEVELOCITY AND DIRECTION OF WIND The air in motion is called wind. The wind blows from high pressure to low pressure Pressure Gradient Force The differences in atmospheric pressure produces a force. The rate of change of pressure with respect to distance is the pressure gradient. The pressure gradient is strong where the isobars are close to each other and is weak where the isobars are apart Frictional Force It affects the speed of the wind. Over the sea surface the friction is minimal
- 11. CORIOLIS FORCE The rotationof the earth about its axis affects the direction of the wind. This force is called the Coriolis force after the French physicist who described it in 1844. It deflects the wind to the right direction in the northern hemisphere and to the left in the southern hemisphere. The Coriolis force is directly proportional to the angle of latitude. It is maximum at the poles and is absent at the equator. The Coriolis force acts perpendicular to the pressure gradient force. The pressure gradient force is perpendicular to an isobar. https://www.pmfias.com/wind-movement-factors-affecting-winds-coriolis-force/
- 12. PRESSURE AND WIND https://www.learner.org/courses/envsci/unit/text.php?unit=2&secNum=6 https://sites.google.com/site/ladiversidadclimatica/los-factores-termodinamicos/circulacion- en-superficie-centros-de-accion-masas-de-aire-y-frentes Thewind circulation around a low is called cyclonic circulation. Around a high it is called anti cyclonic circulation low pressure area the air will converge and rise. Over high pressure area the air will subside from above and diverge at the surface
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- 15. GENERAL CIRCULATION OFTHE ATMOSPHERE The pattern of planetary winds largely depends on : • latitudinal variation of atmospheric heating emergence of pressure belts • the migration of belts following apparent path of the sun • the distribution of continents and oceans • the rotation of earth The general circulation of the atmosphere also affects the oceans. The large-scale winds of the atmosphere initiate large and slow moving currents of the ocean.
- 16. The pattern ofthe movement of the planetary winds is called the general circulation of the atmosphere. The general circulation of the atmosphere also sets in motion the ocean water circulation which influences the earth’s climate GENERAL CIRCULATION OF THE ATMOSPHERE https://commons.wikimedia.org/wiki/File:AtmosphCirc.png
- 19. http://www.mrgscience.com/uploads/2/0/7/9/20796234/9991763_orig.gif The air atthe Inter Tropical Convergence Zone (ITCZ) rises because of convection caused by high insolation and a low pressure is created. The winds from the tropics converge at this low pressure zone. The converged air rises along with the convective cell. It reaches the top of the troposphere up to an altitude of 14 km. and moves towards the poles This causes accumulation of air at about 30o N and S
- 20. Part of theaccumulated air sinks to the ground and forms a subtropical high. Another reason for sinking is the cooling of air when it reaches 30o N and S latitudes. Down below near the land surface the air flows towards the equator as the easterlies. The easterlies from either side of the equator converge in the Inter Tropical Convergence Zone (ITCZ). Such circulations from the surface upwards and vice-versa are called cells. Such a cell in the tropics is called Hadley Cell.
- 21. https://es.m.wikipedia.org/wiki/Archivo:Jetcrosssection.jpg In the middlelatitudes the circulation is that of sinking cold air that comes from the poles and the rising warm air that blows from the subtropical high. At the surface these winds are called westerlies and the cell is known as the Ferrel cell. At polar latitudes the cold dense air subsides near the poles and blows towards middle latitudes as the polar easterlies. This cell is called the polar cell. These three cells set the pattern for the general circulation of the atmosphere. The transfer of heat energy from lower latitudes to higher latitudes maintains the general circulation.
- 22. AIR MASSES The homogenousregions can be the vast ocean surface or vast plains. The air masses are classified according to the source regions a. Warm tropical and subtropical oceans b. The subtropical hot deserts c. The relatively cold high latitude oceans d. The very cold snow covered continents in high latitudes e. Permanently ice covered continents in the Arctic and Antarctica
- 23. • Maritime tropical(mT) • Continental tropical (cT) • Maritime polar (mP) • Continental polar (cP) • Continental arctic (cA) TYPES OF AIR-MASSES
- 24. SEASONAL WIND The patternof wind circulation is modified in different seasons due to the shifting of regions of maximum heating, pressure and wind belts. The most pronounced effect of such a shift is noticed in the monsoons, especially over southeast Asia.
- 25. LOCAL WINDS Differences inthe heating and cooling of earth surfaces and the cycles those develop daily or annually can create several common, local or regional winds.
- 27. LAND AND SEABREEZES
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- 29. FRONTS When two differentair masses meet, the boundary zone between them is called a front. The process of formation of the fronts is known as frontogenesis. There are four types of fronts: • Cold • Warm • Stationary • Occluded
- 30. The fronts occurin middle latitudes and are characterised by steep gradient in temperature and pressure.
- 31. When the coldair moves towards the warm air mass, its contact zone is called the cold front whereas if the warm air mass moves towards the cold air mass, the contact zone is a warm front. If an air mass is fully lifted above the land surface, it is called the occluded front.
- 34. Extra tropical cyclones form alongthe polar front. Initially, the front is stationary. In the northern hemisphere, warm air blows from the south and cold air from the north of the front.
- 36. TROPICAL CYCLONES Tropical cyclonesare violent storms that originate over oceans in tropical areas This is one of the most devastating natural calamities. They are known as Cyclones in the Indian Ocean, Hurricanes in the Atlantic, Typhoons in the Western Pacific and South China Sea, and Willy-willies in the Western Australia
- 37. TROPICAL CYCLONES The conditionsfavorable for the formation and intensification of tropical storms are: • Large sea surface with temperature higher than 27° C • Presence of the Coriolis force • Small variations in the vertical wind speed • A pre-existing weak-low-pressure area or low-level-cyclonic circulation; • Upper divergence above the sea level system
- 38. THUNDERSTORMS AND TORNADOES Thunderstormsare caused by intense convection on moist hot days. A thunderstorm is characterised by intense updraft of rising warm air, which causes the clouds to grow bigger and rise to greater height. This causes precipitation. Later, downdraft brings down to earth the cool air and the rain. These violent storms are the manifestation of the atmosphere’s adjustments to varying energy distribution.
- 39. http://www.teamwildmama.com/id69.html HOW TO READA WEATHER MAP https://www.thoughtco.com/symbols-on-weather-maps-3444369?utm_source=pinterest
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