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Atmosphere & their Structure
- It is a colourless, tasteless and odourless mixture of gases that
surround the earth.
- It extends up to a height of about 1600 km.
- However 99 per cent of total mass of the atmosphere is within
40 km from the earth.
Structure of atmosphere: Based on vertical temperature differences
- It is the lower layer of atmosphere
- Extending up to a height of 8 to 18 km from the earth surface. (RPSC, AA0-09).
- Temperature decreases with increase in altitude at the rate of 6 ‘V /km.
- It influences earth climate.
- It is dense part of atmosphere, contains 85 per cent of the atmosphere’s mass.
- All weather phenomena like clouds, rain, mist, fog, dew etc. occur in troposphere. (JRF, Ph. D -09)
- It lies beyond the height of 8 to 18 km extending up to 50 km.
- Warmest layer, Uniform temperature with altitude.
- It is the actual seat of most of the photochemical reactions in air.
- Presence of Ozone layer, hence also called ozonosphere
- It lies above the stratosphere; a height of 50 km extending up to 80 km from the earth surface.
- Cold region.
- Strong decrease in temperature with increase in altitude.
- It is the outermost layer called exosphere.
- From earth surface extending a height of 80 km up to 1600 km.
- The lower layer of thermosphere is called ionosphere.
- Long distance radio communication is made possible through this ionized layer.
- Temperature increase with altitude.
Composition of atmospheric air: (Gases Volume in %)
- Nitrogen -78.08%
- Oxygen -20.95%
- Argon – 0.93% (RPSC,AA 0-09)
- Carbon dioxide – 0.03%
Composition of soil air :
- Nitrogen percentage is more or less same as in atmosphere.
- Oxygen levels decrease as compared to atmosphere.
- CO2 levels will be nearly 8-10 times more (0.25%) as compare to atmosphere.