Light rain (gentle rain) or Drizzle means not heavy rain.

Rainfall is the amount of rain which falls.

Deluge is a severe flood.

Rainstorm is a storm with heavy rain.

A drop of rain / a droplet / a raindrop is a single drop of rain.

Rainbow is a curved shape of different colours seen in the sky.

Shower is a short period of rain or snow.

Heavy snow / deep snow is great amount of snow.

Light snow means not heavy snow.

Hail is small and hard balls of ice falling from the sky.

Sleet is a snow partly melted.

Wet snow means watery snow.

Melting snow means snow turing from the solid state to the liquid state.

Snowfall means a fall of snow.