As warm air rises into the atmosphere, it cools.

A body of warm air is heavier than a body of cold air.

A front is the area where two different air masses meet.

Clouds are grouped according to their shape and the height at which they occur.

Stratus clouds resemble cotton balls.

The type of rainfall that affects the West of Ireland most is convectional rainfall.

Precipitation occurs in a variety of forms, including rainfall, snow, hail and sleet.

Evaporation, condensation and precipitation are parts of the water cycle.

About one-tenth of all the water on Earth is fresh water.