Chapter 1 Introduction to the Atmosphere The Atmosphere 9e

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					          Chapter 1
Introduction to the Atmosphere
        The Atmosphere 9e
              Lutgens & Tarbuck
       Power Point by Michael C. LoPresto
         Weather and Climate
• Weather is the state of the atmosphere at
  any given time.
• Climate – a description of aggregate
  weather conditions; the sum of all statistical
  weather information that helps describe a
  place or region.
• Weather is constantly changing (hour by
  hour, day by day)

• Climate based on observations over many
                Basic Elements
             of Weather & Climate
• The most important elements are
  –   (1) air temperature,
  –   (2) humidity,
  –   (3) type and amount of cloudiness,
  –   (4) type and amount of precipitation,
  –   (5) air pressure, and
  –   (6) the speed and direction of the wind
• Earth's four spheres include:
  –   the atmosphere (gaseous envelope),
  –   the lithosphere (solid Earth),
  –   the hydrosphere (water portion),
  –   and the biosphere (life).
• Each sphere is composed of many
  interrelated parts and is intertwined with all
  other spheres.
• Lithosphere
  – Core
  – Mantle
  – Crust
• Atmosphere
  – 99% of atmosphere within 30 km of Earth’s
  – Provide air we breathe and protects from UV
• Hydrosphere
  – Water is what makes planet Earth unique
  – Global Ocean
     • 71% of Earth’s surface
     • 97% of Earth’s water
• Biosphere
  – Involves all life on Earth
The Atmosphere:
A Part of the Earth System
• Closed
  – Energy moves in/out, but matter cannot
• Open
  – Both energy/matter move in/out
• Negative Feedback
  – Keep status quo
• Positive Feedback
  – Drive for change
           The Atmosphere
• The life-giving, gaseous envelope that
  surrounds the Earth.

• energy exchanges between the atmosphere
  and Earth’s surface along with space
  produces weather.
• Air is a mixture of many gases, and its
  composition varies

• Two gases, nitrogen (78%) and oxygen
  (21%), make up 99 percent of the volume
  of the remaining clean, dry air.
Composition of the Atmosphere
• Carbon Dioxide - present in small amounts,
  it is very important to meteorology.

• Absorbs energy and leads to a rise in global
  temperature (Greenhouse Effect)
Carbon Dioxide
• Variable Components
• Water vapor - absorbs heat given off by
  Earth as well as some solar energy.
• When water vapor changes from one state
  to another, it absorbs or releases heat.
• In the atmosphere, water vapor transports
  this latent ("hidden") heat from one region
  to another, and it is the energy source that
  helps drive many storms.
• Aerosols act as surfaces on which water can
  – absorbers and reflectors of incoming solar
• Ozone (O3)
  – Concentrated in the stratosphere
  – Absorbs potentially harmful UV rays from the
Ozone Depletion
Formation of Ozone
Sustaining Ozone
Depletion of Ozone
         Thermal Structure of the
• The atmosphere is divided vertically into
  four layers on the basis of temperature
  –   Troposphere
  –   Stratosphere
  –   Mesosphere
  –   Thermosphere
• Layer in which we live, where nearly all
  weather occurs
• Temperature decreases with an increase in
  – Environmental lapse rate – name given to the
    temp. decrease
     • (normal lapse rate- 6.5o per kilometer)
• The ELR is not constant it can change day
  to day
  – In some shallow layers the temp will increase,
    temperature inversion.
  – Near the equator, thermal mixing creates
    thicker layers for the troposphere
  – Closer to the poles, the troposphere is thinner
• The boundary between the stratosphere and
  troposphere is called the tropopause
• Temperatures rise through the atmosphere
• This is due to ozone absorbing UV rays
  – Although the ozone is thinner at top of strat., it
    absorbs enough energy to keep the warmer
• Stratopause marks the end of the
• Temp begins to decrease with height at
• The coldest temps in the atmosphere occur
  in the mesosphere
• The mesopause marks the end of the
  mesosphere and the beginning of the
• No well-defined upper limit
• Although the temp is hot, it would not feel
  hot because there are very few air molecules
• Lower portion of the thermosphere
• Here molecules of nitrogen and oxygen are
• Electrons are then free to travel as electric
• The aurora borealis and aurora australis are
  found here
Structure of the Atmosphere

    Thermal Structure
Pressure Decreases with Altitude
Chapter 1


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