Key for Homework 3

 

The mountain problems were self-grading.

 

  1. List at least 4 different forms of radiation in the earth's atmosphere.

    Answers will vary. Possible answers include light, microwave radiation, infrared radiation, radio waves, ultraviolet radiation, gamma rays, and many others.
     
  2. List three important "greenhouse gases". Which greenhouse gas is not regulated by the Kyoto Protocol?

    Important greenhouse gases include carbon dioxide, water vapor, methane, and CFCs. Water vapor is not regulated by the Kyoto Protocol.
     
  3. What does Wien's Law tell us is the difference between radiation emitted by the sun versus radiation emitted by the earth?

    Since the sun is hotter than the earth, the sun emits radiation primarily at short wavelengths, whereas the earth emits radiation primarily at long wavelengths.

     
  4. What does Stephan/Boltzmann's Law tell us is the difference between radiation emitted by the sun versus radiation emitted by the earth?

    Since the sun is hotter than the earth, the sun emits MORE radiation than the earth does.

     
  5. In class, we said that AT NIGHT clouds help keep the surface of the earth warm. Do they do this during the day also? What other factors are important during the day?

    Clouds DO also absorb and emit longwave radiation by day, although their reflection of shortwave radiation from the sun is a much larger effect during the day. Other important factors during the day include sun angle, length of day, and the albedo of the surface.

     
  6. This is the big question of this homework assignment. Write a paragraph or two explaining heat transport in the atmosphere. Starting with shortwave radiation coming from the sun, what happens to that heat? Your short essay should include the following terms and concepts:

    absorption, reflection, transmission, scattering -- albedo, conduction, convection, advection, longwave radiation, shortwave radiation, greenhouse effect, atmospheric window, Latent heat

    Radiation coming from the sun is shortwave radiation. As this radiation--which is SWdown--encounters the atmosphere, several things may happen. SWdown may be absorbed in the atmosphere (especially ultraviolet radiation by the ozone layer); it may be reflected upwards by clouds and aerosols; it may be scattered by air molecules; or it may be transmitted all the way through the atmosphere to the earth's surface. Depending on the albedo of the surface, shortwave radiation that encounters the surface may be reflected upwards or it may be absorbed by the surface, increasing the temperature of the surface. In turn, the warm surface may heat the atmosphere by conduction, and warm air can transport heat vertically by convection or advection. The warm surface may also result in a transfer of latent heat from the surface to the atmosphere, by evaporation of water at the surface and condensation of water vapor aloft.

    Additionally, the warm surface may emit longwave radiation upwards--LWup. LWup is generally absorbed by atmospheric gases and clouds, which later reemitted the longwave radiation down--LWdown--towards the surface. This process is known as the "Greenhouse Effect". Some of the radiation in the form of LWup will have a very specific wavelength--known as the "atmospheric window"--and radiation with this wavelength is not absorbed by the atmosphere. Therefore, this longwave radiation will be transmitted by the atmosphere into space.