Stratus
Topic: Water in the Atmosphere: Humidity, Condensation, Clouds and Precipitation · NCERT: Class 11, Ch 10 "Water in the Atmosphere"
Meaning
Stratus clouds are flat, grey layers that cover large parts of the sky. They form when air loses heat, or when air masses of different temperatures mix. Stratus makes the sky overcast, meaning fully covered and dull. It may give light drizzle, but not heavy rain.
Example
On winter mornings in the Indo-Gangetic plain, for example around Delhi, dense ground fog often lifts a little as the day warms. It then becomes a low, grey stratus layer that keeps the sky dull for hours.
Don't confuse with
- Fog: fog is a cloud with its base at or near the ground. Stratus floats above the ground.
- Nimbostratus: a thicker, darker layer that gives long spells of steady rain or snow. Plain stratus gives only drizzle.