Cumulus clouds change into cumulonimbus clouds.

Explanation:

Cumulus and cumulonimbus clouds are low clouds. These are at an altitude of fewer than 2000 metres. Cumulus clouds are responsible for pleasant weather. Due to an increase in the vertical flow of air, cumulus clouds get turned into cumulonimbus clouds which leads to rain.

Explanation:

Cumulus and cumulonimbus clouds are low clouds. These are at an altitude of fewer than 2000 metres. Cumulus clouds are responsible for pleasant weather. Due to an increase in the vertical flow of air, cumulus clouds get turned into cumulonimbus clouds which leads to rain.