Transcript The Atmosphere - Orangefield ISD

THE ATMOSPHERE
Environmental Science
Unit 2
THIN BLUE BLANKET
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Atmosphere – mixture of gases, which are mostly
nitrogen and oxygen
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Halo of blue is created when sunlight is scattered by
Earth’s atmosphere
Ozone Shield – Natural Sunscreen
When UV light strikes an oxygen molecule (O2), it
splits the molecule to create free oxygen atoms
 Free oxygen atoms attach to O2 in the air, forming
ozone (O3 )
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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
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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
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Chlorofluorocarbons (CFCs) – compounds that
contain carbon, fluorine, and chlorine
Nontoxic
 Nonflammable
 Inexpensive
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Old coolants were dangerous
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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
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Biological Effects
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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
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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
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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
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Less destructive to ozone layer b/c less stable and fewer
molecules reach stratosphere
 Production must stop by 2030
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Halons – stable chemicals that contain bromine,
fluorine, and carbon
Destroying ozone much faster than CFCs
 Halons in fire extinguishers are being replaced with CO2
 CO2 not suitable for all fires
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WEATHER PATTERNS
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Weather Predictions
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Meteorology – study of the physics and chemistry of
the atmosphere
Weather – atmospheric conditions that result from
interactions between temperature, moisture, winds,
and clouds
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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
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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
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NEXRAD – Doppler radar that can map velocity of
wind currents within a cloud
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Tornado detection
Hurricanes Connie and Diane in 1955 prompted
creation of the National Hurricane Center
Improving Forecasts
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Jet stream – 200 mph river of air that flows 20,00030,000 ft. above Earth
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El Nino – irregular warming of water in East Pacific
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Don’t understand why it moves the way it does
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
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Hydrogen Furnace
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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
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Earth rotates on its own axis from west to east
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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
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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)
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Major air pollution disasters have happened during fall and
winter