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Air makes up the majority of the atmosphere. However,
you have to include particular matter like water and dust to get a
complete picture of our atmosphere. The atmosphere, a thin shell of
gases that envelops the Earth’s surface, is all around us. The
pressure of air decreases with altitude. The average pressure at sea
level is 760 mm Hg (mercury), at 4.8 Km it is about 400 mm Hg, at 16 Km
it is about 40 mm Hg, and at 48 Km it is only 0.1 mm Hg.
Without the atmosphere, the Earth would be very
different. Without gases in the atmosphere, there would be no scattering
of sunlight, so the sky would be black, not blue. Stars and planets
would be visible, even in the day time. With no atmosphere, there would
be no weather; the wind would not blow; and it would never rain.
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Weather is created in the troposphere
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