THE EARTH IS SURROUNDED BY ITS ATMOSPHERE, a blanket of gases that enables life to exist on the planet. This layer has no definite outer edge, gradually becoming thinner until it merges into space, but over 80 percent of atmospheric gases are held by gravity within about 12 miles (20 km) of the Earth’s surface. The atmosphere blocks out much harmful ultraviolet solar radiation, and insulates the Earth against extremes of temperature by limiting both incoming solar radiation and the escape of reradiated heat into space. This natural balance may be distorted by the greenhouse effect, as gases such as carbon dioxide have built up in the atmosphere, trapping more heat. Close to the Earth’s surface, differences in air temperature and pressure cause air to circulate between the equator and poles. This circulation, together with the Coriolis force, gives rise to the prevailing surface winds and the high-level jet streams.
The atmosphere
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GEOLOGY AND GEOGRAPHY AND METEOROLOGY
published on 7:29 AM
THE EARTH IS SURROUNDED BY ITS ATMOSPHERE, a blanket of gases that enables life to exist on the planet. This layer has no definite outer edge, gradually becoming thinner until it merges into space, but over 80 percent of atmospheric gases are held by gravity within about 12 miles (20 km) of the Earth’s surface. The atmosphere blocks out much harmful ultraviolet solar radiation, and insulates the Earth against extremes of temperature by limiting both incoming solar radiation and the escape of reradiated heat into space. This natural balance may be distorted by the greenhouse effect, as gases such as carbon dioxide have built up in the atmosphere, trapping more heat. Close to the Earth’s surface, differences in air temperature and pressure cause air to circulate between the equator and poles. This circulation, together with the Coriolis force, gives rise to the prevailing surface winds and the high-level jet streams.
