The weatherman explained.

(1) The moisture carried in the warm and humid air stream is gaseous water vapor, which meets with cold air, reducing the temperature of the warm and humid air stream. When it is cold, the water vapor in the warm and humid air stream will liquefy into small water droplets and form rainfall. (2) In drought, there must be warm and humid airflow (or a lot of water vapor) in the sky to implement artificial rainfall; During artificial rainfall, dry ice is often thrown into the sky to absorb heat, which lowers the air temperature and makes the water vapor in the air liquefy when it is cold. So the answer is: when it meets cold air, the temperature of warm and humid air drops, and the water vapor in the warm and humid air will liquefy into small water droplets; Dry ice absorbs a lot of heat when sublimating, which reduces the temperature of warm and humid air flow.