Why does it rain? Why is there so much water in the sky?

Hello! The water in the sky comes from the evaporation of ground water. Water on the ground enters the sky in the form of steam under the influence of heat sources such as thermal radiation. Equivalent accumulation to a certain extent, under appropriate conditions (such as strong convection of hot and cold air, etc. ), it can condense into water drops and then fall to the ground, that is, it rains. This evaporates into the air and condenses into water droplets in the form of rain or other forms (such as snow, hail, etc.) after heating. ), this is a kind of circulation of water in nature. I hope I can help you.