Cumulus
Topic: Water in the Atmosphere: Humidity, Condensation, Clouds and Precipitation · NCERT: Class 11, Ch 10 "Water in the Atmosphere"
Meaning
Cumulus clouds look like heaps of cotton wool with flat bases. They appear in scattered patches. They form by convection: the ground heats the air above it, the warm air rises, cools and condenses. The flat base marks the height where condensation begins. NCERT gives their height as 4,000–7,000 m, but fair-weather cumulus usually has its base much lower, at about 1–2 km, and its top rises higher. Cumulus usually means fair weather, but it can grow into a towering cumulonimbus.
Example
On a summer morning over north India, for example over Delhi, small cumulus puffs dot the sky. By afternoon, strong heating can make some of them grow into cumulonimbus. These give the short, stormy rain of pre-monsoon thunderstorms.
Don't confuse with
- Cumulonimbus: a cumulus that has grown very tall, often up to the top of the lowest layer of the atmosphere, with an anvil-shaped top. It brings thunder, lightning, hail and heavy rain. Ordinary cumulus does not.