My Science School

What is a monsoon?

A monsoon is a season of very heavy rain falling in tropical countries. They are most common near the Equator, when seasonal winds spring up, carrying moist air in from the sea. Important crops such as rice depend entirely on the monsoon to provide the right growing conditions. If the monsoon rains fail, famine commonly follows.

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What is smog?

Smog is a serious form of air pollution that can cause breathing problems. The term smog was first used to describe a type of air pollution in London, when smoke from coal fires combined with fog to produce dense yellow clouds that sometimes persisted for days. The term now describes the hazy fog that is caused mainly by vehicle exhausts and smoke from factories. It builds up when there is little air movement, and can happen when a layer of warm air traps cooler air near the ground, preventing the smog from being blown away. Cities in bowls or sheltered valleys are particularly liable to this condition. 

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