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Aviation glossary

Towering Cumulus

What is towering cumulus?

FAA handbook figure illustrating towering cumulus

A tall, building cumulus cloud that signals atmospheric instability, with turbulent air both inside and around it. These clouds often grow into cumulonimbus clouds or full thunderstorms—in fact, towering cumulus is considered the first stage of thunderstorm development. Think of it as a cloud "under construction"—a warning that storms may be brewing.

Also known as: TCU, cumulus congestus

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