Chapter 17 Atmosphere

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Chapter 17 Atmosphere Weather

• 17.1 The Atmosphere in Balance
• 17.2 Heat and the Atmosphere
• 17.3 Local Temperature Variations
• 17.4 Human Impact on the Atmosphere

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17.1 The Atmosphere in Balance

• The atmosphere is like a space suit that has
  changed greatly with time (evolved)
• A. The past atmosphere
• Methane Ammonia (4 Bill. Yrs. Ago by volcanoes)
• Sunlight gtnitrogen, hydrogen carbon dioxide
• Sunlight broke down water vapor to ozone or O3
• Blue-green algae produce oxygen (o2)
• 600 mill. years ago O2 CO2 stabilized

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17.1 The Atmosphere in Balance

• B. The Present Atmosphere
• Gases The two main gases are Nitrogen (N2)
  Oxygen (O2). Other gases are Carbon Dioxide
  (CO2), Water Vapor (H2O) Argon (Ar)
• The atmosphere is stable because it has an
  efficient recycling system.

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17.1 The Atmosphere in Balance

• 1. Nitrogen living organisms need it to make
  protein bacteria in soil release it for plants
• 2. Oxygen essential for respiration combustion
  or burning of fuels
• 3. Carbon Dioxide raw material used by plants
  during photosynthesis, returned by respiration
  "Greenhouse Effect"

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17.2 Heat and the Atmosphere

• A. How Heat Energy Moves
• Three ways Conduction, Convection and
  Radiation
• 1. Conduction-Transfer of heat energy through
  collisions of the atoms or molecules of a
  substance.
• 2. Convection-Transfer of heat energy in a liquid
  or gas through the motion of the liquid or gas
  caused by differences in densities.
• 3. Radiation-Transfer of energy through space in
  the form of visible light, ultraviolet light and
  other types of electromagnetic waves.

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17.2 Heat and the Atmosphere

• B. Structure of the Atmosphere
• Troposphere
• a. Lowest layer, earth's weather
• b. height 6 to 17 km
• c. Convection currents w/n Troposphere (hot air
  rises)
• d. Temperature Drops 6.5C/km
• e. Tropopause-boundary

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17.2 Heat and the Atmosphere

• 2. Stratosphere
• a. Stratosphere to about -60 C50 km
• b. Jet Stream-eastward winds 320 km/hr
• c. Ozone (O3) combined w/ O2 in lightning
• 16-60 km ozonosphere
• absorbs UV light and release heat
• d. Stratopause (18 C) boundary

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17.2 Heat and the Atmosphere

• 3. Mesosphere Thermosphere
• a. 50-90 km Mesosphere, above 90 km
  Thermosphere
• b. Meteoroids burn up (shooting stars)

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17.2 Heat and the Atmosphere

• 4. Ionosphere- lower part of the thermosphere
• a. 90-500 km
• b. Electrically charged atoms-ions
• c. Reflect radio waves
• d. Satellites- weather, communication, and
  defense

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17.2 Heat and the Atmosphere

• C. Insolation and the Atmosphere
• Insolation-Incoming Solar radiation
• The energy transfer from the earth's surface is
  one of the major causes of weather in the
  atmosphere.
• The accumulation of Carbon Dioxide and Water
  Vapor absorb most of the infrared radiation

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17.3 Local Temperature Variations

• A. Intensity of Insolation
• Time of day- Most direct sun rays at noon
• Latitude- Equator receives the most direct sun
  rays. Locations at the poles can receive no
  daylight or daylight all day.

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17.3 Local Temperature Variations

• 3. Time of Year- In the summer the Northern
  Hemisphere gets direct sunshine and the Southern
  Hemisphere is indirect. The opposite happens in
  winter. (remember proximity of Sun)
• 4. Clouds-The intensity of clouds affects the
  amount of insolation that reaches the earth.

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17.3 Local Temperature Variations

• B. Heating of Water and Land
• Water and Land cool at different rates
• Specific Heat- The amount of heat needed to raise
  1 gram of a substance by 1 oC. The specific heat
  of water is almost 3 times that of land.
• Isotherms-Lines that connect places with the same
  temperature.

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17.4 Human Impact on the Atmosphere

• A. Common Air Pollutants
• Air Pollutant- any airborne gas or particle that
  occurs at a concentration capable of harming
  humans or the environment.
• Clean Air Act of 1970- Six key pollutants Carbon
  Monoxide, Nitrogen Dioxide, Sulfur Dioxide,
  Particulate Matter, Lead and Ozone.

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17.4 Human Impact on the Atmosphere

• B. Acid Rain
• Forms when sulfur dioxide and nitrogen oxides mix
  with water.
• Acidity is measured using the pH scale. Ranges
  from 0-14. 7 is neutral. Acid rain is around 5.

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17.4 Human Impact on the Atmosphere

• C. Smog
• Photochemical smog is a brownish haze that forms
  in air polluted with nitrogen oxides and
  hydrocarbons from automobile exhaust.
• Temperature Inversion- An increase in temperature
  with an increase in altitude occurs when a layer
  of cold air is trapped beneath a layer of warm
  air.

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17.4 Human Impact on the Atmosphere

• C. Ozone Depletion
• Caused by Chlorofluorocarbons (CFCs)
• Loss of ozone increases exposure to harmful
  ultraviolet radiation.

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17.4 Human Impact on the Atmosphere

• E. Global Warming
• Average temperatures have increased 1 oC since
  1880.
• Caused by the burning of fossil fuels and global
  deforestation, which raises the amount of CO2 in
  the atmosphere.
• Creates changes in climate, a rise in sea level
  and increased drought.
• An Inconvenient Truth - Science