why snow fall

Dear student,

Most of the time, when condensation occurs in outer atmosphere the clouds break up into small pieces of ice before descending to earth in the form of rain. The friction with the atmosphere due to the speed of travel and the distance cause these small pieces of ice to melt into rain drops. These ice pieces fail to melt by the time they hit the surface of high altitude hills and mountains because the duration of their travel from the clouds to the mountains turns out to be insufficient for the ice to melt. They get deposited in the form of snow on the surface of such hills and mountains. That is why you hardly ever get to hear of snowfall on the plains.

It can also be explained in the following way-
Sometimes, when the pieces of ice are larger than usual it rains hail stones on the plains because they do not get sufficient time to melt before they hit the ground.
Snow forms when tiny ice crystals in clouds stick together to become snowflakes. If enough crystals stick together, they'll become heavy enough to fall to the ground.Snow is formed when temperatures are low and there is moisture in the atmosphere in the form of tiny ice crystals.
Regards