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4.1 Earth’s Atmosphere A. Atmosphere Thin layer of air that protects the Earth’s surface from extreme temperatures and harmful UV (sun) rays B. Theory Volcanoes produced nitrogen and carbon dioxide, but little oxygen Simple organisms began producing oxygen Oxygen formed the ozone layer (03) Green plants and diverse life forms developed C. Composition Solids: dust, salt, pollen Liquids: water droplets, acid from volcanoes Gases: Nitrogen……………………78% Oxygen…………………….21% Carbon Dioxide & Argon…1.0% D. Current Troubles Humans are adding pollutants Energy use Increase in CO2 Global Warming Hole in the ozone layer (Antarctica) E. A Bright Future Wind Energy Solar Energy Bio-fuel Efficient cars Car-pooling Recycling Factory waste minimized F. Atmospheric Pressure As Earth’s gravity pulls gases toward its surface, weight presses down on the air below Molecules nearest to surface- closer together Greater air pressure at surface As altitude increases, pressure decreases Fewer molecules…harder to breathe Foldable Directions 1. Take 3 pieces of computer paper. 2. Layer the 3 pieces about an 1 ½ apart. 3. Fold the bottom layers up so there is 6 tabs showing. 4. Label as follows: Exosphere Thermosphere Mesosphere Stratosphere Troposphere Earth’s Surface Troposphere 0 to 10 km Lowest layer Weather 99% of atmosphere water vapor 75% of atmosphere gases Stratosphere 10 to 50 km Ozone layer (O3) Jet pilots fly here to avoid storms Mesosphere 50 km to 85 km Shooting stars Contains part of the ionosphere Thermosphere 85 to 500 km Thickest layer Coldest temps. Highest temps (3600 F) Contains part of the ionosphere Exosphere Stretches to 5500 miles No weather Warm temperatures Few air molecules Space shuttles 4.2 Energy Transfer in the Atmosphere What percent of the sun’s energy is absorbed and reflected by the Earth? UV Rays Absorbed – 50% absorbed by Earth’s surface – 15% absorbed by the atmosphere 65% *Refer to page 99 in your textbook UV Rays Reflected – 25% reflected by clouds – 6% reflected by the atmosphere – 4% reflected by Earth’s surface 35% Process How is energy transferred? Radiation Rays or waves Conduction Convection Sun, x-rays, tanning bed Contact Sand-feet, spoon-pan Flow of air molecules Oven, air in room Water in our Atmosphere Hydrosphere – All water on earth Conservation – Water is never created or destroyed Why is Earth Suitable for Life? Planet Atmosphere Venus -gases are very dense -atm. traps heat (too hot) Mars -atm. too thin to support life (too cold) Earth -O2 / CO2 balance -water cycle -ozone protection 4.3 Air Movement A. Wind Movement of air from an area of higher pressure to an area of lower pressure Warm Air Cold Air Low High Pressure Low High Density Effects -rises -replaced by cooler air -sinks -replaces warm air B. Weather is determined by: 1. Coriolis Effect- rotation of the Earth causes moving air and water to appear to turn right north of the equator and left south of the equator 2. Cool Air replacing warm air -this determines when and where planes and ships travel C. Jet Streams Narrow belts of strong winds that blow near the top of the troposphere Faster in the winter because the difference between cold air and warm air is greater D. Convection Currents Sea Breeze Land Breeze What happens? Land heats Land cools faster than water faster than water Where? Toward land Toward sea When? day night E. Global Winds Location Description Prevailing Westerlies 30 degrees N. & S. latitude (most of U.S.) Earth’s rotation deflects air to east as it moves to poles Doldrums along the equator heat causes air to expand: zone of low pressure Trade Winds between 30 degrees N. and 30 degrees S. of equator Polar Easterlies b/c of coriolis effect, winds curve back to equator 60 degrees to the N. and cold, dense air sinks S. pole & moves away from poles