The Atmosphere APES

Composition of atmosphere 7 major components Nitrogen 78% Oxygen 21% Water Vapor 0-4% Carbon Dioxide <<1% Methane <<<1% Nitrous Oxide <<<1% Ozone <<<1% Nitrogen: Fundamental nutrient for living organisms. Nitrogen fixing into soils, denitrification back into air Oxygen: Produced through photosynthesis; used in cellular respiration Water Vapor: greater near equator, lower at poles Carbon Dioxide: Major greenhouse gas; increased about 24% last 300 years; humans 5,500 million tons of CO2 per years; average CO2 molecule in the air for 100 years Methane: Greenhouse gas; since 1750 methane has increased by 150%; 400 million tons/year by humans; life in atmos is 10 years Nitrous oxide: greenhouse gas; increasing by 0.3%/year; source burning fossil fuels, fertilizers, deforestation; humans add 6 million tons/year; Ozone: 97% found in stratosphere (ozone layer) about 9-35 miles above surface; absorbs UV radiation; “hole” occurs over Antarctica; broken down by CFCs (primary source)

Layers of the Atmosphere Troposphere Stratosphere Mesosphere Thermosphere (ionosphere) Troposphere: 0-7 miles: 75% of atmosphere’s mass; temperature decreases with height -76F at top; weather in this zone Stratosphere: temperature increases with altitude because of heat absorption by ozone; contains ozone layer Mesosphere: temp. decrease with altitude; coldest layer; ice clouds; meteors burn up here Thermosphere or Ionosphere: Temp. increases with height due to gamma and x-rays, UV radiation; aurora borealis occur here;

Factors that Influence Climate Air mass Air pressure Albedo Altitude Angle of Sunlight Clouds Distance to ocean Fronts Heat Land (geography) Land Changes Latitude Location Humidity Mountains Pollution Earth Rotation Wind Patterns Human Activity

Air Pressure Unequal heating of Earth Warm air rises – low pressure clouds Cool air sinks – high pressure Clear Wind – air movement from H – L Coriolis pulls to right in NH

Global Circulation

Tornadoes Tornadoes Tornado Alley Windsor Tornado Fujita Scale Average ¼ mile wide Tornado Alley Windsor Tornado May 22, 2008 F3 1 Mile Wide

Hurricanes Most severe weather phenomenon Average size – 100 miles Celia – 80 mile diameter Carla – 500 mile diameter Katrina – 240 mile diameter

ENSO = El Niño ENSO – El Niño Southern Oscillation Next to the seasons, El Niño is the most powerful force driving global weather Usually occurs in December Dryer than normal across Pacific Northwest Colder winters in southeast and southwest U.S.A Effects of El Niño

La Niña La Niña is characterized by unusually cold ocean temperatures in the Equatorial Pacific Nearly opposite effects of El Nino Wetter than normal N.W. USA Increase in Atlantic hurricanes Heavier than normal monsoons in India and S.E. Asia Colder winters in Canada and N.E. USA Warmer and drier winters in the S.W. and S.E. USA