Archive for the ‘Atmosphere’ Category
August 21st, 2009 | 
Author: The earth is surrounded by a thick blanket of air, called the atmosphere, which is made up of about 20 gases. The two main gases are oxygen and nitrogen. It also contains water vapour and dust particles. Air is matter and, like all matter, it has weight. Weight is the measure of the pull of gravity on matter. Earth’s gravity pulls on each particle of gas and dust in the atmosphere. If it was possible to place this on a pair of scales it would weigh about 5,700,000,000,000,000 tonnes! Thus earth’s atmosphere is one of the things that make it a planet of life.
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