IR Cloud Top Temperature Example

How does cloud altitude and moisture in the upper atmosphere alter the appearance of IR imagery?

This is a water vapor image compiled from radiometers flown on several geostationary satellites. A part of the image has been extracted and appears as a square below the larger satellite image. This portion of the image contains a cloud and some clear sky areas. You can change the appearance of this extracted image by changing the cloud altitude (and its associated ambient air temperature) or the humidity of the upper troposphere (approximately 200 to 600 mb). You do this by moving the sliding scales (scroll bars) accompanying the picture on the right.

The vertical scale changes the cloud altitude and its temperature. The numbers on each side of figure show the altitude and corresponding temperature.

You can modify the amount of water vapor in the upper troposphere with the horizontal sliding scale.

Questions to consider:

What cloud levels can water vapor imagery best observe?
Can high cirrus and clear sky conditions always be discriminated in the imagery?
How does changing the humidity affect the image?

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This educational applet was developed by Tom Whittaker and Steve Ackerman of the Department of Atmospheric and Oceanic Sciences and the Space Science and Engineering Center at the University of Wisconsin-Madison.