Atmosphere, Climate and Weather
The atmosphere of the Earth serves as a key factor in sustaining the planetary ecosystem. The thin layer of gases that envelops the Earth is held in place by the planet's gravity. Dry air consists of 78% nitrogen, 21% oxygen, 1% argon and other inert gases, such as carbon dioxide. The remaining gases are often referred to as trace gases, among which are the greenhouse gases such as water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Filtered air includes trace amounts of many other chemical compounds. Air also contains a variable amount of water vapor and suspensions of water droplets and ice crystals seen as clouds. Many natural substances may be present in tiny amounts in an unfiltered air sample, including dust, pollen and spores, sea spray, volcanic ash, and meteoroids. Various industrial pollutants also may be present, such as chlorine (elementary or in compounds), fluorine compounds, elemental mercury, and sulphur compounds such as sulphur dioxide .
The ozone layer of the Earth's atmosphere plays an important role in depleting the amount of ultraviolet (UV) radiation that reaches the surface. As DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.
Read more about this topic: Natural Environment
Famous quotes containing the words climate and/or weather:
“Then climate is a great impediment to idle persons; we often resolve to give up the care of the weather, but still we regard the clouds and the rain.”
—Ralph Waldo Emerson (1803–1882)
“When the weather is bad as it was yesterday, everybody, almost everybody, feels cross and gloomy. Our thin linen tents—about like a fish seine, the deep mud, the irregular mails, the never to-be-seen paymasters, and “the rest of mankind,” are growled about in “old-soldier” style. But a fine day like today has turned out brightens and cheers us all. We people in camp are merely big children, wayward and changeable.”
—Rutherford Birchard Hayes (1822–1893)