All cloud types
“Mid-level pixel clusters in the digital atmosphere”
Formation
Convective rolls in mid-atmosphere, orographic lifting
Weather signal
Possible afternoon thunderstorms
Technical specs
Altitude6,500-20,000 ft
AppearanceGray/white patches or layers, larger than cirrocumulus
Fun factIf seen in the morning, thunderstorms are likely by late afternoon.
common
Etymology
Latin: 'altus' (high) + 'cumulus' (heap)