Quick Reference

THE ATMOSPHERE

The atmosphere is divided into a number of layers, each with its own set of conditions. The constituents of the atmosphere are the same throughout.

troposphere. (0-10km). Contains most of the weather and clouds. The temperature usually decreases with height.

tropopause. Boundary between the troposphere and stratosphere.

stratosphere. (10-50km). Nacreous clouds and most of the ozone. Temperature increases slowly with height.

mesosphere. (50-80km). Noctilucent clouds. Temperature decreases with height.

ionosphere. (80-400km). Radio reflective layer of electrically charged nitrogen and oxygen particles.

thermosphere. (80-500km). Temperature increases with height.

exosphere. (>500km). Beyond the atmosphere.

invariables. Nitrogen 78%, oxygen 21%, argon 1%. Less than 1%: neon, helium, methane, krypton, hydrogen, nitrous-oxide, xenon.

variables. Water vapour 0.0 to 0.7%, carbon-dioxide 0.01 to 0.1% (average 0.034%), ozone up to 0.000007%.

contaminants. Sulphur-dioxide <0.0001%, nitrogen-dioxide <0.000002%, traces of ammonia and carbon-monoxide.