1. STABLE AND UNSTABLE ATMOSPHERE

2. LAPSE RATE
NORMAL LAPSE RATE – 1 degree C per 160 mt
ENVIRONMENTAL LAPSE RATE – the natural lapse rate as the air is ascending.
DRY ADIABATIC RATE – cooling by expansion is far more imp than any other process so far as condensation in free air is concerned. This type of cooling is due to lifting of the air. Since an ascending air undergoes even decreasing pressure exerted on it. It expands and cools. Such temp changes are brought about without any heat added or subtract from the rising air. This is unsaturated air cools at the dry adiabatic cooling.

3. Rising Air Cooler than Environment Tends Toward Stability

4. WET OR MOIST ADIABATIC LAPSE RATE
after passing beyond the condensation level, the latent heat of condensation lowers the rate of cooling, because of this process small decrease in lapse rate. This modified rate of cooling is called wet or moist adiabatic cooling.

5. DRY ADIABATIC LAPSE RATE

6. Air Cools at Dry Adiabatic Rate until Reaching Dew Point Then Cools at Wet Adiabatic Rate

7. STABILITY If an object is slightly disturbed from it’s original position tends to return to the same it is said stable equilibrium. “ stability is the condition in the atmosphere in with vertical motion are absent or definitely restricted” At ground temp of air is 40 deg C Dry adiabatic lapse rate is 10 deg C/ km Normal (envi) lapse rate is 6.5 deg C / km in this case the temp of ascending air is 30 deg C While the temp of surrounding air is 33.5 deg C So ascending air being colder than surrounding air would descend and atmospheric stability caused

8. ABSOLUTE STABILITY
some time the normal lapse rate is less than wet adiabatic lapse rate even at condensation point. Further vertical movement of air is stopped and such air is called absolutely stable. This condition is known as absolute stability.
temperature inversion is typical example of absolute stability.

10. ABSOLUTE INSTABILITY
at every level of elevation the distribution of temp, environmental lapse rate is greater than the dry adiabatic lapse rate. The air has tendency to continuously move upward till its temp become equal to that of surrounding air.
such a state of continued vertical movement of ascending air is called as absolute instability.

11. LAPSE RATE
NORMAL LAPSE RATE – 1 degree C per 160 mt
ENVIRONMENTAL LAPSE RATE – the natural lapse rate as the air is ascending.
DRY ADIABATIC RATE – cooling by expansion is far more imp than any other process so far as condensation in free air is concerned. This type of cooling is due to lifting of the air. Since an ascending air undergoes even decreasing pressure exerted on it. It expands and cools. Such temp changes are brought about without any heat added or subtract from the rising air. This is unsaturated air cools at the dry adiabatic cooling.
Environmental lapse rate is greater than dry adiabatic rate

12. CONDITIONAL INSTABILITY – when a parcel of air is forced to move upward it cools at dry adiabatic lapse rate (10 deg C/ km) where as normal rate is (6.5 deg C / km ). After rising to certain height a air become saturated and a latent heat of condensation is added to rising air cools at wet adiabatic lapse rate( 5 deg C / km ) rises air upward due to normal rate is greater. Then move upward automatically. Due to its own properties after condensation point is reached.