Question

-----------------type of clouds are indicators of storm

Answer 1

HEY mate !! HERE is your answer !!
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I think it should be STORMY clouds. But I am not 100% sure.
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Hope it helps you.

^_^

Answer 2

Answer: Cumulonimbus clouds

Explanation:  The word cumulonimbus comprises of two words . Cumulus which in Latin means 'pile' whereas nimbus means 'rain cloud.

Cumulonimbus clouds usually bring rain and thunderstorms. These  are large and tall clouds which can grow upto 10 km high and are usually dark at the bottom. In fact, they are sometimes called thunderstorm clouds which not only bring heavy rainfall but also lead to weather disruptions like lightning, tornadoes, hail and snow showers.

These clouds comprises of tiny droplets of water but since these clouds are formed at greater heights the droplets freezes there because of cold temperature. This gives the outer part of the cloud a little fuzzy look without clear edges.