Question

How are clouds formed ?

Answer 1

Hint: Clouds consist of water droplets and ice crystals that are fine enough that they are able to stay in the air. There are many different types of clouds that are formed due to different conditions, for example cumulus, mammatus, altocumulus, cirrocumulus and many more.

Complete step by step answer:
The formation of clouds can be explained in a stepwise manner:
Step 1: Evaporation of water
Water from oceans, rivers and other sources evaporates into air as water vapour. The heat of vaporization (also called latent heat or enthalpy of evaporation) is the change in enthalpy that happens when a given amount of a substance present in liquid phase changes into vapour phase at a constant temperature and pressure conditions. The molar enthalpy of vaporization of water at normal atmospheric pressure is 40660 J/mol.

Step 2: Condensation of water vapours
When the air containing the water vapours rises above it subsequently gets cooler. Since at higher altitudes the atmospheric pressure is low, therefore this air is under low pressure. Due to low temperature and low pressure, the air no longer can hold the water vapour and hence the water vapour converts into droplets and ice crystals. The presence of dust and pollen helps in this condensation process and eventually there are enough water droplets on the condensation nuclei (dust, pollen or any other particle) that clouds are formed.

Some clouds are formed in this way. But the formation of some clouds such as lenticular and stratus clouds involve wind blowing into the side of a mountain range or other terrain due to which the wind is cast upwards in the atmosphere.

Also the collision of two large masses of air at the earth’s surface gives rise to clouds.

Hence clouds are formed because of vaporization of water and condensation of the water vapours into water droplets.

Note: You might be wondering why the air containing the water vapour rises above. This is because the air present near the earth’s surface gets heated from the ground surface. So, it becomes warm and warm air is lighter and less dense. Therefore the warm air rises above.