Composition & structure of the atmosphere

Composition & structure of the atmosphere

1. Composition & Structure of the Atmosphere

2. Atmosphere The thin layer of gas that envelopes the Earth and is held to the Earth by the force of gravity

3. Composition of Atmosphere 1.Constant Gases 78 % Nitrogen 21% Oxygen 2. Variable gases CO2= 0.04% of air Water Vapours Ozone

4. Layered Structure 4 layers 1.Troposphere 2.Stratosphere 3.Mesosphere 4.Thermosphere

5. Temperature trend

6. Troposphere •Bottom layer •Average height=12km •Temperature decreases with altitude •Lapse rate (rate of decline in temperature)=6.5◦C/1000m •The upper boundary is called tropopause

7. Stratosphere Extends from 12km-50km •Exhibits positive lapse rate (called inversion) •It has calm, thin and clear air •Jets and aircrafts fly in the stratosphere •It contains ozone

8. Mesosphere Extends from 50km-80km above the Earth’s surface •Temperature again increases with height •Here sunlight can form ionized particles and it is called a D-layer •D layer is used for radio communication

9. Thermosphere Extended from 80km to the edge of space •Temperature increases very sharply •Ionization forms E and F layers •These ions can form Auroras due to their movement

10. Aurora