Storm architecture · accessory
Pileus clouds
A cloud wearing a little hat
Full credit
Own work
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Full credit
Own work
Displayed at reduced resolution. See the original file for full licensing information.
Full credit
Own work
Displayed at reduced resolution. See the original file for full licensing information.
Swipe or scroll sideways to explore the photographs. Photos may include other cloud types; names and credits come from their source records.
Spot it
A smooth cap perched above a growing cloud tower.
How it forms
A rising tower lifts a moist layer above it into condensation.
Read the sky
It suggests active upward growth, but the cap alone cannot predict a storm’s strength.
Where to look
Look above rapidly growing cumulus or cumulonimbus.
Little sky facts
Reveal fact 1
Pileus is an accessory cloud.
Reveal fact 2
A tower may grow through its cap.
Reveal fact 3
Several caps can occur at different levels.
Reveal fact 4
The cap is smoother than the cauliflower-like cloud below.
Try this
Compare the smooth hat with the bumpy tower below.
Draw your own cloud ↗Read a little deeper
Conditions described here are places to look, not a global frequency ranking. Use local weather forecasts and warnings for decisions. Never look directly at the Sun.