ST 215 Handout, 9/10/09
Vertical Structure of the Atmosphere
LAYERA (km)P (atm)T (oC)COMMENTS
Exosphere500+0103+Edge of space, light gases escape
Thermosphere90+10-7-90 to103Stable, Solar absorption by O and O2
Mesosphere60-90 10-50 to -90Mixed layer, coldest region
Stratosphere20-5010-2-40 to 0Stable, Solar UV absorbed by O3
Troposphere0-101 to 0.140 to-40Layer of weather, water vapor rules
Beach Ball Earth
Sphere
Rotating
Tilted
Revolving
Sun (light and tides)
Oceans
Continents
Clouds
Ice Sheets
Deserts
Mountains
Life (O2)
Precipitation
Temp. differences
Winds
Lightning
Aurora
Moon (tides)
Natural Greenhouse Effect
Orbit “wobbles” long-term
Stratospheric Ozone
Artificial satellites
Air pollution
Political boundaries
It’s Your Atmosphere
Only planet with abundant O2 atmosphere.
Oceans cover 2/3 of planet.
Natural greenhouse effect keeps urface temperatures 40 to -40 C allows three phases of water (ice, liquid, vapor)
Hydrologic cycle recycles fresh water for the biosphere.
Atmosphere protects earth from UV, meteorites, solar wind.
“Ocean of air” is very thin;we can’t breathe above 10 km.
Air is absolutely necessary for life:
Eat 3 x per day, can survive without food for 40 days.
Drink 6 x per day, can survive without water for 7 days.
Breathe 22,000 x per day, can live without air only 3-5 min.
1022 molecules in every breath of air
1044 molecules in the entire atmosphere
1022 breaths of air in the atmosphere.
Composition (major constituents)
Nitrogen78.08%
Oxygen 20.95%
Water Vapor 0 to 4%
Argon0.93%
CO20.0387% = 387 ppm
Weather Elements
Air TemperatureThermometer
Air PressureBarometer
HumidityPsychrometer
CloudsTypes and amounts
PrecipitationLiquid or Frozen
VisibilityFor Aviation
WindSpeed and Direction
Air QualityPollution Load
Definitions
Weather:The state of the atmosphere at a given place and time. Weather elements: T, P, humidity, clouds, precipitation, visibility, wind, air quality.
Meteorology: Scientific study of the weather. Ancient meaning (Aristotle) was much broader.
Climate: Aggregate of regional weather conditions over time. Usually a 30-year average over a region plus a statement about frequency of extreme conditions, such as lightning strikes, tornadoes, hurricanes or drought.
Climatology: Scientific study of climate. Includes fields such as applied climatology, climate modeling, and climate dynamics.
Physical Oceanography: Chemistry and dynamics of oceans, including currents, waves, air-sea interaction, and topics such as El Niño and La Niña.
Atmospheric Science: Umbrella term covering proliferation of research specialties since the mid-1950s. Meteorology, Climatology, Cloud Physics, Atmospheric Chemistry, Numerical Weather Prediction, Satellite and Radar Meteorology, etc.
Global Change or Earth System Science: Umbrella term for study of the complex interactions of the atmosphere, lithosphere, hydrosphere, and biosphere on all temporal and spatial scales plus the human or social dimensions of environmental change.