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The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by Earth's gravity. The atmosphere serves as a ...
The composition of Earth's atmosphere is determined by the by-products of the life that it sustains. Dry air (mixture of gases) from Earth's atmosphere contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and traces of hydrogen, helium, and other "noble" gases (by volume), but generally a variable amount of water vapor is ...
Earth's atmosphere has no definite boundary, gradually becoming thinner and fading into outer space. [218] Three-quarters of the atmosphere's mass is contained within the first 11 km (6.8 mi) of the surface; this lowest layer is called the troposphere. [219] Energy from the Sun heats this layer, and the surface below, causing expansion of the air.
The heliopause is the final known boundary between the heliosphere and the interstellar space that is filled with material, especially plasma, not from the Earth's own star, the Sun, but from other stars. [46] Even so, just outside the heliosphere (i.e. the "solar bubble") there is a transitional region, as detected by Voyager 1. [47]
The Earth's weather is a consequence of its illumination by the Sun and the laws of thermodynamics. The atmospheric circulation can be viewed as a heat engine driven by the Sun's energy and whose energy sink, ultimately, is the blackness of space. The work produced by that engine causes the motion of the masses of air, and in that process it ...
The atmosphere envelops the earth and extends hundreds of kilometres from the surface. It consists mostly of inert nitrogen (78%), oxygen (21%) and argon (0.9%). [4] Some trace gases in the atmosphere, such as water vapour and carbon dioxide, are the gases most important for the workings of the climate system, as they are greenhouse gases which allow visible light from the Sun to penetrate to ...
The density of the Earth's atmosphere decreases nearly exponentially with altitude. The total mass of the atmosphere is M = ρ A H ≃ 1 kg/cm 2 within a column of one square centimeter above the ground (with ρ A = 1.29 kg/m 3 the atmospheric density on the ground at z = 0 m altitude, and H ≃ 8 km the average atmospheric scale height).
The top of the mesosphere, called the mesopause, is the coldest part of Earth's atmosphere. [8] Temperatures in the upper mesosphere fall as low as about −100 °C (173 K; −148 °F), [ 9 ] varying according to latitude and season .