Chapter 14 By: Vanessa LaTorre

 Atmosphere - thin envelope/layer of gas around Earth  Gases stretch 375 miles above sea level  Composed of gases known as air  Permanent gases – maintain constant level  Nitrogen, oxygen, argon, neon, helium, hydrogen, xenon

 Variable gases – levels vary in atmosphere  Water vapor  Carbon dioxide  Methane  Ozone gas  Nitrous oxide  Chlorofluorocarbons

 5 distinct layers:  Troposphere – closest to the Earth – 7 miles thick  Temperature decreases with height  Transitional layer called the tropopause  6 miles thick  Also called isothermal layer  Temperature is constant as you increase height

 Stratosphere – inversion miles above Earth  Rises to height of 30 miles  Temperature increase – temperature increases with altitude  Ozone layer  Blocks U.V. radiation from the Sun  Approximately 10 miles above Earth  Transition layer – called stratopause

 Mesosphere – 35 miles above Earth  Air temperature decreases as height increases  Transition layer – mesopause  Thermosphere – 60 miles above Earth  Temperature increases with height  Exosphere miles above Earth  Air molecules escape gravitational pull

 Important aspect of atmosphere is the ionosphere  High concentrations of ions  Formed by incoming solar radiation  During day 37 miles above Earth  At night 75 miles above Earth  Ionosphere is approximately 200 miles thick  Important for radio communication on Earth