The Internet Companion provides access to many different types of information. Some relate directly to concepts and issues developed in the accompanying text while others allow the user to explore additional subjects in greater depth.

This exercise is intended to explore how clouds affect the radiation balance of the earth.

Images used for illustration:

• Visible image
• Visible image: high res
• Visible image: altered color table
• IR image: colors as would be recorded in space
• IR image: inverted colors
• Water Vapor image

  Enter your response to each question in the blanks provided. The cursor has to be in the box in order to enter a response. Be sure to fill out all of the fields.
  Then click submit when you are finished to hand in your answers.

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  Examining Satellite Imagery
  

  Visible imagery from geostationary satellites provide an indication of the amount of solar radiation reflected back to space. Objects that reflect solar radiation strongly appear white in the image while objects that primarily absorb solar radiation appear dark. Albedo refers to the fraction of incoming solar radiation that is reflected back to space.

  Begin by clicking here for a sample visible satellite image.

  Answer the following questions in the space provided below.

  1. Identify in the image at least one location on the surface of the earth where the albedo is very high.

  2. Identify in the image a couple of regions where significant amounts of clouds are present and the albedo is high.

  3. Identify in the image at least one region where the albedo is low.

  Infrared imagery in the 10-11 micron range indicates the amount of infrared radation emitted to space. From the Stefan-Boltzmann Law it is possible to relate large amounts of emitted radiation to warm surfaces and relatively small amounts of emitted radiation to cool surfaces. Since temperature decreases strongly with height through the troposphere, high clouds emit less radiation to space than low clouds. The convention for infrared imagery used in the atmospheric sciences is to represent large amounts of infrared radiation emitted to space (warm temperatures) by dark colors and small amounts of infrared radiation (cool temperatures) by light colors.

  Continue by clicking here for an infrared image for the same time as that of the visible image above. Answer the following questions in the space provided below.

  4. Identify in the image at least one region where large amounts of infrared radiation are emitted to space.

  5. Identify in the image at least one region where the radiating temperature at which the infrared energy is being emitted is relatively cold.

  Effective Radiating Level of CLouds
  As discussed in Chapter 2 of the accompanying text, clouds have a significant impact on the radiation budget of the atmosphere. Clouds contribute both to warming of the surface of the earth and cooling of the surface of the earth depending on the level at which they are radiating to space.

  The combined application of visible and infrared imagery makes it possible to determine the relative radiating level of clouds. Thick clouds whose tops are low appear white in visible imagery (as a result of their high albedo) while they appear gray in infrared imagery ( as a result of their relatively high temperature). Thick clouds whose tops are in the upper troposphere appear white in both visible and infrared imagery, since they are both reflective and cold. Thin clouds in the upper troposphere appear bright white in infrared imagery but are difficult to detect in visbile imagery.

  Using the 2 satellite images above, answer the following questions.

  6. Identify at least one location where low, thick clouds are prevalent.

  7. Identify at least one location where high, thick clouds are prevalent.

  8. Identify at least one location where thin, high clouds are prevalent.

  9. In which locations are clouds contributing primarily to warming of the earth's surface? Why?

  10. In which locations are clouds contributing primarily to cooling of the earth's surface? Why?

  Due Date September 15, 2000 Click to hand in your answers.