Page 40 - Fundamentals of Air Pollution

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The Natural versus

Polluted Atmosphere

Pollution, n: the action of polluting; the condition of being polluted. Pollute, vt:
[L. pollutus, past part, or polluere, to make physically impure or unclean]; to defile,
desecrate, profane-syn. see CONTAMINATE. Air, n: [fr. L aer, fr. Gr. aer] 1. the
mixture of invisible tasteless gases which surrounds the earth . Atmosphere, n: [fr.
Gr. (atmo and sphaira) 2. the whole mass of air surrounding the earth . . .'

I. THE ATMOSPHERE

On a macroscale (Fig. 2-1) as temperature varies with altitude, so does
density (1). In general, the air grows progressively less dense as we move
upward from the troposphere through the stratosphere and the chemo-
sphere to the ionosphere. In the upper reaches of the ionosphere, the
gaseous molecules are few and far between as compared with the tropo-
sphere.
The ionosphere and chemosphere are of interest to space scientists be-
cause they must be traversed by space vehicles en route to or from the

Definitions are from "Webster's Tenth New Collegiate Dictionary," 10th ed. Merriam,
Springfield, MA, 1993.
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