View
216
Download
0
Tags:
Embed Size (px)
Citation preview
Gases in Atmospheres
• Volatiles in Molecular Form (ice or gas):– Carbon dioxide CO2 (molecular weight = 44)– Oxygen O2 (molecular weight = 32)– Nitrogen N2 (molecular weight = 28)– Water H2O (molecular weight = 18)
• Other gases:– Argon Ar (molecular weight = 40)– Neon Ne (molecular weight = 20)
• Jovian gases:– Ammonia NH3 (17), Methane CH4 (16), Helium He (4),
and Hydrogen H2 (2)
Light and Atmospheres
• Greenhouse gases absorb infrared light
• Scattering of visible wavelengths depends on wavelength
• Molecular dissociation by ultraviolet light
• Ionization by X-rays
Atmospheric Layers
Greenhouse Effect
Blue Sky: Scattered Light
UV and X-ray Light
• Ozone (O3) in stratosphere of Earth absorbs ultraviolet light.– Chemical balance between O3 and O2
– Chlorofluorocarbons (CFCs) destroy ozone
• X-rays ionize the upper layers of the atmosphere (ionosphere)– Charged particles reflect low frequency radio
waves (e.g., AM radio)
Temperature Profiles
Magnetosphere
Convection
Convection on Earth
Wind Patterns on Earth
Water Cycle on Earth
Creation of Terrestrial Atmosphere
Loss of Atmosphere
Thermal Escape of Gas
Retaining an Atmosphere
• Gas will have a lifetime of several billion years if the escape velocity is 10 times the rms velocity
Become Aware of Greenhouse Effect!