How Do Clouds Form

Clouds are a parcel of water droplets that float freely in the air in the upper atmosphere. The process of formation of clouds starts when the ground gets heated up due to the radiation from the sun. The heated surface of the earth leads to the increase in the temperature of the air close to the surface. Since the heated air is lighter than the surrounding cooler air, this parcel of heated air begins to rise in the atmosphere. This process continues for a long period of time as the lighter parcel or air continues to displace the cooler sections above and reaches a high altitude.

Simultaneously, another process takes place in the parcel of water vapor. As the parcel rises higher in the atmosphere, the surrounding temperature decreases, thereby, leading to the lowering of the water vapor holding capacity of the air. Thus, this parcel of air that holds the maximum amount of water vapor possible at a particular temperature is called saturated and the water vapor begins to condense to form tiny droplets of water. This temperature is termed as dew point temperature when the water vapor changes into water droplets. It would also be worth noting that the decrease in temperature with height occurs at a rate of approximately 10 degree Celsius with every 1000 meters and this rate is referred to as ‘adiabatic lapse rate’.

The process continues till a point when the clouds reach a good altitude wherein the surrounding temperature of the atmosphere is similar to the temperature within the parcel of air and water vapor, which can now be termed as a cloud. This temperature is termed as ‘equilibrium temperature’. Once this point is reached the cloud is kept afloat by the wind currents that carry it from one place to another. However, it is worth noting here that the formation of clouds occurs in the upper troposphere. This is the main mechanism involved in the formation of clouds in most areas. In some areas, the hot parcel of air, ascends through the slope of the mountain if the wind currents are favorable.

The height of the cloud depends on the average temperature of the day. For instance, on a hot sunny day, the clouds are formed at a greater height as compared to a cold winter day. The explanation for this lies in the fact that on a cold day the equilibrium temperature is attained at a relatively lesser height and vice versa.

The color of the cloud visible to the naked eye depends on the size of the droplets in it. If the droplets are small, a bright colored cloud is seen and when the water droplets are thicker and closely packed, darker clouds are visible.