What happens to atoms in the air when it rains?

Answer 1

The atoms or molecules in the air get pushed aside by the raindrops as they fall through, then the molocules close back up behind the raindrops. It's the same thing that happens when anything moves through the air.

Answer 2

During rainfall, water droplets form as a result of condensation of water vapor in the air. These droplets grow larger as they collide with other droplets and particles in the atmosphere, eventually becoming heavy enough to fall as rain. The air itself remains largely unchanged, with the water droplets acting as carriers for the water molecules.