the portion of the atmosphere above the troposphere.
Compare upper air.
Origin of upper atmosphere
First recorded in 1890–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
meteorol that part of the atmosphere above the troposphere
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
The part of the atmosphere above the troposphere. The upper atmosphere includes the mesosphere, the ionosphere, the thermosphere, and the exosphere. Temperatures in the upper atmosphere decrease with increasing altitude except in the thermosphere, where temperatures increase significantly with altitude, because the few molecules present receive intense solar radiation.
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