Winds occur due to unequal heating of atmospheric air. The heat causes rising up of air along with water vapour. As the air rises, it expands and cools. This cooling causes the water vapour in the air to condense. The condensation of water occurs if some particles (like dust particles) act as the ‘nucleus’ for these drops to stick around. These tiny droplets grow bigger by more and more condensation of other water droplets and finally form the clouds.
