Cloud
Topic: Water in the Atmosphere: Humidity, Condensation, Clouds and Precipitation · NCERT: Class 11, Ch 10 "Water in the Atmosphere"
Meaning
A cloud is a mass of tiny water droplets or ice crystals. It forms when water vapour condenses in free air well above the ground. Condensation means vapour turning into liquid when air cools to its dew point. Clouds are grouped by height, spread, density and transparency into four basic types: cirrus, cumulus, stratus and nimbus. Clouds give us rain, snow and hail. They also shade the Earth by day and keep it warm at night.
Example
In June, the south-west monsoon winds blow onto the Kerala coast and rise up the Western Ghats. The moist air cools, and thick rain clouds build over the windward slopes and bring heavy rain.
Don't confuse with
- Fog: fog is also condensed water in the air, but its base is at or near the ground and it cuts visibility below 1 km. A cloud forms well above the ground.