Evolution of the atmosphere

Article By:

Holland, Heinrich D. Department of Geological and Geophysical Sciences, Harvard University, Cambridge, Massachusetts.

Last reviewed:September 2020

DOI:https://doi.org/10.1036/1097-8542.058900

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• Evolution of the atmosphere, published November 2019:Download PDF Get Adobe Acrobat Reader

Variation with time of the chemical composition and total weight of the Earth's atmosphere. The atmosphere is a most tenuous envelope; its mass is less than one-millionth that of the solid Earth; its density even at sea level is less than one-thousandth that of rocks, and virtually all of the atmosphere is below a height only one-hundredth of an earth radius above the surface of the Earth. But the atmosphere is taken so much for granted that one tends to be surprised at the thought that it has a history, that its chemical composition and total weight have varied through time (Fig. 1). On reflection, it would, however, be odd to find that the atmosphere has not changed during the long years of the Earth's existence, and that its weight and composition have not responded to the complicated series of events that have left such clear marks on the Earth's crust.

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