Cold wave
Topic: Natural Hazards and Disaster Management in India · NCERT: Class 7, Ch 3 "Climates of India"; Class 11, Ch 4 "Climate"; Class 11, Ch 6 "Natural Hazards and Disasters: Causes, Consequences and Management"
Meaning
A cold wave is a spell of days when temperatures fall far below normal. In India it mostly hits the northwest from December to February. Two things cause it. First, snow falls on the nearby Himalayan mountains. Second, cold winds blow in from the Caspian Sea and Turkmenistan region. Cold waves bring frost (ice crystals that form on the ground and on plants) and thick fog. These harm crops, slow down road, rail and air travel, and endanger poor and homeless people. "Frost or cold wave" is on India's list of notified disasters, so relief can be paid from the State Disaster Response Fund.
Example
In December-January, cold waves sweep across Punjab, Haryana and Delhi in the northwest plains. They bring frost to wheat fields and dense fog that delays trains and flights.
Don't confuse with
- Frost: frost is one result of a cold wave. It is the ice that forms on surfaces. A cold wave is the whole spell of very cold weather.
- Heat wave: a heat wave is the opposite. It is a spell of very hot, dry weather (the loo) over northwest India in April-June.