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Atmosphere, Energy Transfer, and Air Movement Mr. Ross, 7th Science I. The Atmosphere A. Importance of the Atmosphere 1. Atmosphere- a thin layer of air forming a protective layer around the planet 2. Keeps the temperature in a range that supports life 3. It protects life from the Sun’s harmful rays B. Makeup of the Atmosphere 1. Mixture of solids, liquids, and gases. Extends from the crust to outer space. 2. Early Atmosphere was created by volcano eruptions. a) was mostly Nitrogen and CO2 b) Small organisms gave ate CO2 and released Oxygen c) An ozone layer (O3)formed to protect organisms from harmful sun rays d) Plants evolved and changed more CO2 into O2 3. Gases in the Atmosphere a) 78%= Nitrogen (N2) b) 21%= Oxygen (O2) c) 0.93%=Argon 0.03%=Carbon Dioxide (CO2) d) 0.04%= Other gases (Methane, Hydrogen, Krypton, Xenon, Ozone, ect.) e) Water Vapor can also make up about 4% of the atmosphere 4. Solids and Liquids in the Atmosphere a) Solid particles include dust, pollen, salt (from ocean spray) b) Liquids include water droplets and other liquids C. Layers of the Atmosphere 1. Troposphere- Lowest layer of the atmosphere; where weather happens a) contains 99% of water vapor and 75% of atmospheric gases b) Extends from earth to 10 km high Troposphere! 2. Stratosphere- Extends from 10 km to 50 km; contains the Ozone layer a) Ozone layer protects us from harmful UV rays 3. Mesosphere-Extends from 50 km to 85 km; place where shooting stars occur 4. Thermosphere- thickest layer, extends from 85 km to 500 km. a) contains the Ionosphereelectrically charged particles that bounce radio waves over long distances 5. Exosphere- the area beyond 500 km, the beginning of outer space OZONE LAYER Which Layer does it happen in? A severe Thunderstorm Shooting Stars Satellites orbit Earth Ozone layer absorbs UV rays Place where AM radio waves reflect back to earth Which Layer does it happen in? A severe Thunderstorm : Troposphere Shooting Stars: Mesosphere Satellites orbit Earth: Exosphere Ozone layer absorbs UV rays: Stratosphere Place where AM radio waves reflect back to earth: Thermosphere D. Temperature/Pressure in Atmosphere 1. Pressure- force exerted on an area 2. Pressure in the atmosphere increases as you move closer towards earth a) Like a pile of football players—the player on the bottom of the pile feels the most weight. b)The player on top feels the least weight 3. At sea level, the air pressure is about 15 pounds per square inch. SO, on your head right now, you feel about 1200 pounds of pressure on your head from AIR! 4. Sun is the source of energy for earth; but this energy must pass thru atmosphere a) Troposphere is warmed by the earth (which is warmed by sun); every kilometer you climb, the temperature drops 6.5° C b) Ozone absorbs sun energy, making the upper stratosphere warm up c) Mesosphere temperatures drop with altitude (like the Troposphere) d) The thermosphere and exosphere are the first to receive the sun’s rays, so the temperature is very high E. Ozone 1. Ozone layer is between 19 and 48 km; made of molecules of oxygen (O3) 2. Absorbs most of the Ultraviolet Rays from the sun (Harmful rays) a) UV rays can cause mutations, especially skin cancer 3. Ozone is destroyed by CFCs, a chemical that was used in aerosol sprays, air conditioners, foam and refrigerators. 4. There was a hole in the Ozone layer near Antarctica because of CFCs 5. CFCs were banned, and the Ozone hole has started to close up again II. Energy Transfer in the Atmosphere A. Energy from the sun 1. Energy on earth comes mostly from the SUN!!!! a) Sun energy goes to plants, plant energy goes to animals, and so on. 2. Energy from the sun can be…. a) Reflected by the atmosphere (6%), clouds (25%), or earth’s surface (4%) b) Absorbed by the atmosphere (15%) or by Earth’s surface (50%) 3. Life exists on earth because it holds just the right amount of energy and reflects just the right amount. This keeps the temperature at a good level B. Heat 1. Heat is energy that flows from an object of higher temperature to an object of lower temperature. 2. Heat is transferred by Radiation, conduction, and convection 3. Radiation- energy transferred in the form of rays or waves a) radiant energy from the sun warms your face! b) Sun’s heating of water (to cause evaporation) is radiation 4. Conduction- transfer of energy when molecules bump into each other a) hot sand warms your feet by conduction b) Air near earth’s surface is heated by conduction c) water vapor in the air loses energy to the atmosphere by conduction 5. Convection- transfer of heat by the flow of material. a) Cool air sinks and pushes hot air out of the way, creating a convection current Radiation, Conduction, or Convection You feel the heat from a light bulb You feel the heat from touching a hot pot The roof of your mouth burns when you bite into a piece of cheese pizza Radiation, Conduction, or Convection Your feet are colder than your head in a hot shower Your hands are cold when you grab a cold Pop can A ceiling fan that is turned on cools the whole room III. Air Movement A. Forming Wind 1. Wind is the movement of air from an area of higher pressure to lower pressure. 2. Uneven heating of the earth (since earth is curved) causes some parts of earth to be heated more than others a) The equator receives direct sun rays, the north and south poles receive slanted rays, and so they receive less heat b) This causes different areas of density and pressure 3. Winds are named by where they come from a) Winds that come from the west are Westerlies (even though they move towards the east) What is the Wind’s name? Wind Blowing east Wind Blowing west Wind Blowing Southeast Wind Blowing Northeast Westerly Wind Easterly wind Northwest wind Southwest wind 4. Cold, HIGH pressure air comes from the poles 5. Warm, LOW pressure air comes from the equator 6. Coriolis Effect-rotation of the earth causes moving air and water to turn right when north of the equator, and left when south of the equator B. Surface Winds 1. Doldrums- near the equator, even heating causes no wind (no pressure difference), and lots of rain (hot air rises, cools, and then precipitates) 2. Westerlies- near 30° to 60° North and South, earth’s rotation deflects air and moves wind from west to east 3. Trade Winds- Coriolis effect deflects air from east to west from 0° to 30° N or S 4. Polar Easterlies- air moves from east to west near the North and South poles C. Winds in the Troposphere 1. Jet Streams-narrow belts of strong winds; blow near the top of the troposphere 2. Polar Jet Stream forms a boundary of cold air between cold, dry polar air in the north, and warm, moist air to the south a) Polar Jet stream moves faster in the Winter, because the difference in temperature/ pressure is greater b) Saves planes fuel when traveling west to east by flying in the jet stream c) Planes traveling east to west avoid the jet stream to save more fuel D. Local Wind Systems 1. Smaller wind systems affect local weather a) Land and sea breezes occur near large bodies of water (oceans, lakes) 2. Sea breeze- created by land near water during the day by convection currents a) solar radiation warms the land more than the water b)Air over land is heated by conduction c)warm air rises over land, and cooler (high pressure) air from the water moves underneath 3. Land Breeze- movement of air from land towards the sea at night a) At night, the air over land cools faster, the high pressure air is over land b) Low pressure (warm) air over water rises, gets pushed out of the way by high pressure air from the land http://www.classzone.com/books/earth_science/terc/content/visualization s/es1903/es1903page01.cfm?chapter_no=visualization Next Stop: WEATHER