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HE

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TMOSPHERE

Environmental Science Unit 2

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HIN

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LUE

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LANKET

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Atmosphere – mixture of gases, which are mostly nitrogen and oxygen

 Halo of blue is created when sunlight is scattered by Earth’s atmosphere 

Ozone Shield – Natural Sunscreen

  When UV light strikes an oxygen molecule (O 2 ), it splits the molecule to create free oxygen atoms Free oxygen atoms attach to O ozone (O 3 ) 2 in the air, forming

   Most of Earth’s ozone forms a protective filter within the stratosphere Ozone breaks down in the presence of certain chemicals Variations in amount of UV and upper atmosphere temp. cause natural swings in ozone concentration  If system is balanced, rate of ozone formation is equal to rate of destruction (equilibrium)

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CFCs – Risks and Benefits of Technology

   Chlorofluorocarbons (CFCs) – compounds that contain carbon, fluorine, and chlorine    Nontoxic Nonflammable Inexpensive Old coolants were dangerous  Methyl chloride leaks caused many deaths in 1920s First safe coolant was CFC-12 (freon)

   CFCs slowly rise into the stratosphere, where sun’s UV rays split chlorine from the CFC molecules, and chlorine attacks the ozone molecules History of CFCs – p. 93

Biological Effects

  Stratospheric ozone prevents most of the Sun’s UV rays from reaching Earth UVB radiation is harmful to most organisms and is absorbed ONLY by ozone

    UVB causes premature aging of the skin, skin cancer, and cataracts Increase in UVB exposure lowers response of immune system Sunlight is necessary for photosynthesis, but UV light is not UVA and UVB decrease photosynthesis, growth, and reproduction of phytoplankton

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Warning Not Heeded

    World Plan of Action on the Ozone Layer was created in 1977 to encourage countries to ban use of CFCs in aerosols CFCs were essential industrial chemicals, and alternatives were not readily available 1985 – 50% decrease in ozone concentration over Antarctica Ozone being destroyed faster than natural processes can replace it  Increased incidents of skin cancer

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Montreal Protocol

  Chlorine is major cause of ozone destruction 35 countries signed the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987   Goal is total elimination of production and use of the chemicals that deplete the ozone layer Stratospheric ozone level is lowest since measurement began in 1978  UVB radiation at highest level

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Finding Alternatives

   Use of all new CFCs has been banned in industrialized countries Recycled CFCs may still be used to maintain existing equipment High cost of CFC substitutes has encouraged illegal marketing  A/C units and refrigerators now contain HCFCs, which contain hydrogen   Less destructive to ozone layer b/c less stable and fewer molecules reach stratosphere Production must stop by 2030

 Halons – stable chemicals that contain bromine, fluorine, and carbon   Destroying ozone much faster than CFCs Halons in fire extinguishers are being replaced with CO 2  CO 2 not suitable for all fires

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EATHER

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ATTERNS

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Weather Predictions

 Meteorology – study of the physics and chemistry of the atmosphere   Weather – atmospheric conditions that result from interactions between temperature, moisture, winds, and clouds  Behaves according to scientific laws, so weather can be predicted Wildlife behavior often changes when weather is going to change    Cats groom their coats more often when a storm is approaching Deer and cattle feed earlier and longer before a storm If elk begin migrating out of the high country during late fall, it means that heavy snowstorms are on the way

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Weather Forecast

 U.S. has most advanced weather forecast system in the world     Environmental satellites  Global view  Constantly monitor atmospheric conditions Geostationary Operational Environmental Satellite (GOES)  2 orbit Earth at same rotational speed  Short-range forecasts Polar-Orbiting Environmental Satellite (POES)  Collect data from remote ocean areas  Long-range forecasts Weather balloons and aircraft

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Storm Warnings

  NEXRAD – Doppler radar that can map velocity of wind currents within a cloud  Tornado detection Hurricanes Connie and Diane in 1955 prompted creation of the National Hurricane Center 

Improving Forecasts

   Jet stream – 200 mph river of air that flows 20,000 30,000 ft. above Earth  Don’t understand why it moves the way it does El Nino – irregular warming of water in East Pacific  May hold key to seasonal forecasting Long-range weather forecasts will require better understanding of connections between ocean water temps and weather patterns

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All weather is due to the interactions of four things

    Sun Earth’s atmosphere Shape and movement of Earth Shape and make-up of Earth’s surface

Hydrogen Furnace

 Sun produces energy by fusion

Air Around Us

    Atmosphere enables life on Earth Greenhouse effect Clouds – airborne masses of microscopic water droplets or ice crystals Smoke, salt, dust, etc. provide surfaces for condensation of water vapor (condensation nuclei)

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Seasonal Weather

  Earth rotates on its own axis from west to east  Determines direction of prevailing winds and ocean currents Tilt of Earth creates 4 seasons

Down to Earth

 Water needs a very large amount of heat to change its temperature (high specific heat)     Differences in temperatures of land and water create differences in air pressure that causes air movement Humans change local weather  Brick, concrete, asphalt, buildings hold heat Normally, atmosphere temps decrease w/ altitude Inversion – condition where layer of warmer air covers layer of cooler air (fog)  Major air pollution disasters have happened during fall and winter