Now, when this water vapour is at a higher altitude, it condenses due to cold. This water vapour turns into water. Extremely small, tiny water droplets. When these water droplets are suspended in the air, we see clouds. Actually, these are clouds. These small water droplets that make up the clouds are minuscule. So small that their diameter is one-hundredth of a millimetre. And there are millions of such droplets in a cloud. If a cloud is at an even higher altitude, the atmosphere is even colder.
This means that not only does it condense, but it also freezes. These water droplets turn into tiny crystals of ice and these ice crystals form the clouds. So, in this sense, there are two types of clouds. One is made of water droplets and the other is made of ice crystals. The difference between the two can be easily seen. The ice crystal clouds are at a higher altitude. You cannot see a clear boundary line and they are thinner. The heavy clouds that are closer to the ground are made of water droplets.
Now that we have understood this, the next question is how do these clouds rain? What happens is that these small droplets, when they keep accumulating, more droplets keep joining in, the clouds keep getting bigger, these small droplets start colliding with each other, they mix with each other and form big droplets. These big droplets go up into the atmosphere and freeze to form ice crystals but the ice crystals also collide into each other to form bigger ice crystals.
