How are clouds formed ? Describe the three types of clouds based on their average height.
Clouds are formed mainly by the adiabatic cooling of air below its dew point. This cooling process is most effectively created by upward movement of light and warm moist air, which in turn reduces pressure, expands and reaches its dew point. With further cooling below dew point, condensation takes place in air forming clouds.
On the basis of formation, clouds are classified into two main classes :
(i) Cumuliform or Heap Clouds : They are of great vertical height.
(ii) Stratiform or Layer Clouds : They have layered structure.
On the basis of the height, clouds are classified into three classes. They are :
(i) Low Clouds : They are formed upto 2000 metres. Stratocumulus, nimbostratus, cumulus, cumulonimbus and stratus are well known low clouds.
(ii) Medium Clouds : They are formed upto 6000 metres. Alcocumulus and altostratus clouds are the well known medium clouds.
(iii) High Clouds (5-14 km) : Stratus clouds are layered clouds and with uniform layers. These clouds are formed mainly during winter and cause drizzle.
