CLIMATOLOGY
Atmosphere is mixture of different gases, it contains oxygen which is essential for existence of life on earth. The atmosphere consists of different layers with varying density and temperature.
Atmosphere
The atmosphere is thick gaseous envelope which surrounds the Earth from all sides and attached to the earths surface by gravitational force.
The atmosphere also serves as a shield blocking out much of the Sun's Ultraviolet radiation as well as protecting us from showers of meteors.
The atmosphere allows the short wave insolation to pass through it, but becomes opaque for the outgoing long wave terrestrial radiation.
In this way, it acts as a huge greenhouse and maintains an average 15°C temperature on the Earths surface.
STRUCTURE OF ATMOSPHERE:
Atmosphere can be divided into 5 different layers:
1. Troposphere
Troposphere is the lower most layer of atmosphere with average altitude 13 km and extends roughly upto 8 km near the poles and about 18 km at the equator due to strong conventional current. This layer contains 75% of the total gaseous mass, dust particles and water vapours.
The layer experiences gradual decrease in temperature with increase in altitude in a constant rate at 1 ° C for every 165 m (6.5°C /km) called normal lapse rate. All Weather and climatic phenomenous are occurred in this layer. The troposphere is separated from next layer stratosphere by tropopause, which shows nearly constant temperature and of course shows temperature inversion as its temperature near poles is - 45° C and at equator is about - 80° C.
2. Stratosphere
Stratosphere extends above the tropopause to about 50 km high and lacks any atmospheric turbulence, so jet airways are flown in this layer. The lower stratosphere sometimes have cirrous clouds.
The air temperature is steadily increased with altitude due to absorption of UV rays by ozone Layer, but temperature never go above the melting point of water (0 ° C ). Stratosphere is separated from mesosphere by stratopause which has stable thermal condition.
3. Mesosphere
Mesosphere is a frigid atmospheric layer with coldest atmospheric conditions extends upto 80 km from stratopause. Temperature decreases here with altitude and reaches upto 100 ° C .
Meteors burn up in mesosphere as Shooting Stars. It is separated from the Thermosphere by mesopause.
4. Thermosphere
Thermosphere extends from mesopause to about 640 km altitude. Its lower level is called as ionosphere due to presence of free radical or ionic particles. Ionosphere has many thermal layers D-layer, E-layer etc and separated from each other by gradients pause .
Its upper level or above 640 km is called as Exosphere. It is upper most layer of atmosphere, where gases are most rarefied and abundance in electrically charged particles
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