cumulus

Everyday

1. Cumulus is a type of white, puffy cloud with a flat bottom and a rounded top, like cotton wool. tree →
2. Cumulus clouds usually mean fine weather, but very tall ones can grow into storm clouds (cumulonimbus). tree →

In the lessons

In science and geography lessons on weather, cumulus clouds form when warm air rises; they are the clouds children draw. The name comes from Latin "heap". Compare with stratus (flat layers) and cirrus (high, wispy). Phrases: cumulus clouds, fair-weather cumulus, cumulonimbus.

Examples

• Fluffy cumulus clouds floated across the blue sky. tree →
• Cumulus clouds look like cotton wool. tree →
• A cumulus cloud has a flat bottom and a puffy top. tree →
• Big cumulonimbus clouds can bring thunderstorms. tree →
• We drew cumulus, stratus and cirrus clouds in science. tree →
• The cumulus clouds meant it would stay sunny. tree →

Note

Pronounced "KYOO-myoo-lus". Usually uncountable or "cumulus clouds". Related word: cumulative (adding up step by step), from the same Latin root meaning heap.