KnowHow team explains: Clouds are mostly made of tiny droplets of water or ice crystals (if it’s cold enough). These droplets have very low drop velocity. So they continue to float with the surrounding air.

The radius of each droplet varies from a few microns (thousandth of a millimetre) to more than ten microns. The speed with which a body falls is proportional to its mass and surface area. That is why a feather falls with a velocity lower than that of a pebble thrown from the same height.

It has been observed that for particles that are roughly spherical, mass is proportional to the radius cubed, and the downward facing surface of such a particle is proportional to the radius squared. Thus, as a tiny water droplet grows, its mass becomes more important than its shape and the droplet falls faster.

Upward vertical motions in the air also contribute to the floating appearance of clouds by offsetting the small fall velocities of their constituent particles. Clouds generally form, survive and grow in the air that is moving upward. Rising air expands as the pressure on it decreases, and this expansion into thinner, high-altitude air causes cooling. This process makes water vapour condense, which contributes to the survival and growth of the clouds.

The question was sent by

Sushil Mahato from Purulia