Paper I · 4 Geography of India & AP · APPSC Paper I
4.1.4 Atmosphere, temperature, pressure and winds notes
9 notes, in reading order.
- 4.1.4.1Composition of the atmosphere: gases, water vapour and aerosols
The atmosphere is a mixture of permanent gases (mostly nitrogen and oxygen), variable gases such as carbon dioxide and ozone, water vapour and solid particles; the small, variable parts matter most for weather and climate.
Standard · 7 min · Full course - 4.1.4.2Structure of the atmosphere: troposphere to exosphere and the ionosphere
On the basis of temperature, the atmosphere has five layers: the troposphere (weather), stratosphere (ozone), mesosphere (coldest), thermosphere with the ionosphere (radio waves) and the exosphere, which fades into space.
Standard · 7 min · Full course - 4.1.4.3Insolation: factors controlling its distribution
Insolation is the solar energy received at the Earth's surface; how much a place gets depends on the angle of the Sun's rays, the length of the day, the transparency of the air and the slope and aspect of the land.
Standard · 7 min · Full course - 4.1.4.4Heat budget of the Earth: conduction, convection, radiation and albedo
Over a year the Earth neither gains nor loses heat on the whole: of 100 units of insolation, 35 are reflected (albedo) and 65 absorbed, and all 65 are radiated back to space; the tropics have a surplus and the poles a deficit, which winds and currents even out.
Standard · 7 min · Full course - 4.1.4.5Distribution of temperature: isotherms, annual range and temperature inversion
Air temperature depends on latitude, altitude, distance from the sea, air masses and ocean currents; isotherm maps show these controls, the annual range shows continentality, and an inversion is the case where air gets warmer, not colder, with height.
Standard · 7 min · Full course - 4.1.4.6Pressure belts of the world and their seasonal shifting
Pressure falls quickly with height and varies across the Earth in four pairs of belts (equatorial low, subtropical highs, subpolar lows, polar highs) that move north and south with the apparent movement of the Sun.
Standard · 7 min · Full course - 4.1.4.7Planetary winds: Coriolis force, trades, westerlies, polar easterlies and the three-cell model
Winds blow from high to low pressure, are bent by the Earth's rotation (Coriolis force) and slowed by friction; on a global scale this gives the trade winds, westerlies and polar easterlies, organised in three cells in each hemisphere.
Standard · 8 min · Full course - 4.1.4.8Periodic and local winds: monsoons, land and sea breezes, Foehn, Chinook, Loo and others
Besides the planetary winds, some winds reverse with the season (monsoons), some reverse every day (land–sea and mountain–valley breezes), and many local winds get their character, hot or cold, dry or moist, from the land they cross.
Standard · 8 min · Full course - 4.1.4.9Jet streams: subtropical and polar front jets and their effects
Jet streams are narrow, fast-flowing bands of wind near the tropopause, mostly westerly, which steer storms in the middle latitudes and play a key part in the onset and withdrawal of the Indian monsoon.
Standard · 7 min · Full course
Practise Atmosphere, temperature, pressure and winds. Questions with answers explained, from the same topics.
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