Why does it rain?

Rain is water drops falling from the clouds. Water on land and sea surface evaporates into steam. Steam rises to a certain height and turns into water droplets when it is cold. These small water droplets form clouds. They collide with each other in the cloud and merge into large water droplets. When it is too big for the air, it will fall from the clouds and form rain.

As rivers, lakes and oceans are exposed to sunlight, water becomes steam. Water vapor rises into small water droplets and finally becomes clouds. The water droplets or ice crystals that make up the cloud are supported by the airflow below, and the rising airflow continuously transports the water vapor below to the cloud. Small water droplets and small ice crystals in the cloud collide with each other in motion, and the volume will increase. The water droplets in the lower layer of the cloud gradually get bigger. After the volume of ice crystals in the upper layer of the cloud increases, they will fall between the water droplets in the lower part of the cloud, and the water droplets will become bigger and bigger. When these water droplets are too big for the updraft to contain them, it will rain.