Bay Area Earth Science Institute BAESI

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Bay Area Earth Science Institute (BAESI)

• Energy in the Atmosphere
• San Jose State University,
• January 24, 2004
• http//www.met.sjsu.edu/baesi/

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The vertical temperature structure of the
atmosphere
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There are three modes of energy transmission in
the atmosphere.
Energy transmission

• Conduction the transfer of energy in a
  substance by means of molecular excitation
  without any net external motion.
  
• Convection the transfer of energy by mass
  motions within a fluid or gas, resulting in
  actual transport of energy.
  
• Radiation the propagation of electromagnetic
  waves through space.

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Electromagnetic radiation
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• Radiation is the transfer of energy by rapid
  oscillations of electromagnetic fields.
  
• The most important general characteristic is its
  wavelength (?), ____________________________.
  
• Radiation travels through space at the speed of
  light (3 x 108 m s-1).

Defined as the crest-to-crest distance
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Atmospheric Greenhouse Effect

• The atmosphere absorbs some of the Earths
  outgoing longwave radiation.
  
• Which atmospheric gases are most responsible for
  the greenhouse effect?
  

In general, the atmosphere acts like a blanket
absorbing the Earths outgoing longwave
radiation.

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Atmospheric Greenhouse Effect

• The atmosphere absorbs some of the Earths
  outgoing longwave radiation.
  
• Which atmospheric gases are most responsible for
  the greenhouse effect?
  

Water, Carbon Dioxide (CO2)
In general, the atmosphere acts like a blanket
absorbing the Earths outgoing longwave
radiation.

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• Figure 1.2 The Earths annual and global mean
  energy balance. Of the incoming solar radiation,
  49 (168 Wm-2) is absorbed by the surface. That
  heat is returned to the atmosphere as sensible
  heat, as evapotranspiration (latent heat) and as
  thermal infrared radiation. Most of this
  radiation is absorbed by the atmosphere, which in
  turn emits radiation both up and down. The
  radiation lost to space comes from cloud tops and
  atmospheric regions much colder than the surface.
  This causes a greenhouse effect.
• http//www.grida.no/climate/ipcc_tar/wg1/041.htm1
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Sun angle
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Sun angle
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What month do you think this graph represents?
a) December b) March c) June d) September
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What month do you think this graph represents?
a) December b) March c) June d) September
Answer December
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