Frost
Also called: White frost, Hoar frost · Topic: Water in the Atmosphere: Humidity, Condensation, Clouds and Precipitation · NCERT: Class 11, Ch 10 "Water in the Atmosphere"
Meaning
Frost is a layer of tiny ice crystals that forms on cold surfaces when the dew point is at or below 0 °C. Instead of turning into water drops, the vapour turns straight into ice. It forms in the same conditions as dew:
- clear skies;
- calm air;
- high humidity;
- long, cold nights.
Ground frost can kill or damage young plants and standing crops.
Example
In December and January, ground frost in north India, in states such as Punjab, Haryana and Uttar Pradesh, damages potato, mustard and vegetable crops.
Don't confuse with
- Dew: it forms when the dew point is above freezing, so it is liquid drops, not ice.
- Snow: it falls from clouds as ice crystals joined into flakes. Frost forms directly on the ground and on plants.