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Weather The Atmosphere

Weather The Atmosphere

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Weather The Atmosphere

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  1. WeatherThe Atmosphere

  2. Solar Radiation Insolation • radiant solar energy (not insulation) • long wavelengths = lower e • short wavelengths = higher E • short wave from the sun reach the Earth, heat the ground and reradiates into space as longer wave (heat) - which is insulated by the thicker troposphere atmosphere • additionally, radioactive material in the Earth’s core and mantle are also radiating “heat” energy upward thru the crust

  3. Heat Transfer via a) Radiation • Solar Radiation or insolation (short wave) is absorbed by the Earth and re-radiated as long wave, then insulated by the atmosphere and water vapour • Radiometric decay within the earth also produces a smaller amount of heat 1. Solar Constant • amount of insolation received on a surface perpendicular to the sun’s rays • varies w/ solar activity, e.g., sun spots 2. Net Radiation • incoming – outgoing radiation • greatest at the equator (net gain) lowest at the poles (net loss)

  4. b) Convection • the movement of heat by air currents (circular cells, cf. Hadely cell) • advection - horizontal movement c) Conduction • the movement of heat by contact, • from the area of warmth to coolness (Equator to Pole) • insolation + conduction = greatest cumulative effect at 35°

  5. Atmospheric Composition 1. Primary Composition a) Permanent Gases • Nitrogen (78%) • Oxygen (21%) b) Variable Gases • Water vapour (up to 4%) • Carbon Dioxide (incr. 0.034%)

  6. Layers of the Atmosphere a) Troposphere (0-15km) • (grk. “mixing, turbulent”) • base layer • greatest conc. of atmospheric gases, and water • site of weather • Tropopause (temp. -50°C) • Jet Stream (upper Troposphere –Tropopause-lower Stratosphere) • Jet traffic

  7. b) Stratosphere (15-45km) • Ozone layer • absorbs excess ultraviolet - known mutagen/carcinogen, in excess • Temp. - lower portion isothermal • atm. begins to warm with elev. to 0°C(due to E trapped by O3) • pollution (NO2) degrades ozone layer • Stratopause c) Mesosphere (45-80km) • temp. drop from 0 to -50°C • Mesopause

  8. d) Ionosphere (100-300km) • extends thru upper Mesosphere & thru the lower Thermosphere • region of electrically charged particles (electron dense) • radio reflection • Aurorae: Borealis (Northern Lights), Australis (Southern Lights) • interaction of Solar storms of Earth’s magnetic field e) Thermosphere (80-1,300 km) • v. thin atmosphere • Temp.: climbs from -50 to 3000°C plus • Exosphere - uppermost layer of Thermosphere (700km up) edge of space

  9. Albedo • reflectiveness of Earth’s surfaces • e.g., mirror 100% albedo - reflects insolation back into space = cooling • Snow 90% - reflects more E than absorbs • Clouds 50% • Grassland 25% • Forest 20% - absorbs more E than reflects (photosynthesis) • Asphalt 10% • Open water 8%