much of the infrared portion of the electromagnetic spectrum. Since air's capacity to hold moisture drops with temperature, astronomers build infrared telescopes on high mountain tops where the air is much cooler and therefore drier than at lower elevations. Infrared telescopes are also carried on airplanes like NASA's Gerard P. Kuiper Airborne Observatory from which observations can be taken at altitudes above 12,000 meters. Another good location for viewing is Antarctica because of its dry air. Telescopes in space gain an even better view of infrared radiation.

The second demonstration illustrates the effect of small water droplets on light passage. The third demonstration shows that clouds are very effective filters of visible light.

For Further Research:
  • Use a sling psychrometer or other humidity measuring device to determine the relative humidity of the atmosphere. Does the absolute humidity in the atmosphere change with the air temperature? Is there a difference in the clarity of the atmo-sphere between warm and cold nights?
  • Design an experiment to compare the water capacity of warm and cold air.
  • Obtain black and white pictures of Earth from space and estimate the total cloud coverage visible.
  • Is it better to locate an observatory on a high or low point above sea level? Why?
  • Take your class to a science museum that has exhibits on atmospheric phenomena.

Next page Teacher Resources


Last modified prior to September, 2000 by the Windows Team

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