Weather satellites allow scientists to measure land, sea and polar temperatures as well as determine the formation and movement of clouds. Using this information they can predict fronts, precipitation, and storms.
Meteorologists use two types of imaging to get information about clouds: visual and infrared. Visual is a photograph of light in the visible range taken by a satellite. These images are high resolution, which can give us a good idea of the texture and thickness of a cloud. Brighter white on a visual images indicates a thicker cloud.
Infrared is a picture of the heat signature of the cloud. Like any other known object in the universe, clouds produce electromagnetic radiation in the infrared as a result of their temperature. Like other objects, the higher the temperature of the clouds the higher the frequency of the electromagnetic wave. Cool clouds will produce low frequency waves and warmer clouds will produce high frequency waves. Therefore, by looking at the frequency we can infer the temperature.
Cloud temperature corresponds to height, since the atmosphere is warmer closer to the ground and cooler farther away from the Earth. This means that high frequency clouds are cold and low frequency clouds are warm. Cloud height is important because clouds at higher altitudes tend to cause storms.
Infrared imagery of clouds works similarly to an infrared camera in that it looks like a photograph of heat signatures, except infrared images of clouds are in black and white. Brighter white areas on an infrared image of clouds are higher frequency and thus very cold; dimmer, darker gray areas are warmer.
The advantage of infrared is that it can give us information about cloud heights and temperatures 24 hours a day, while visual pictures of clouds are only useful during the daytime. Some disadvantages of infrared are that infrared images are lower resolution, and some very low clouds are similar in temperature to the ground and so don’t show up.
By combining visual pictures of clouds and infrared, meteorologists can get a better idea of how clouds will influence the weather. If an area is bright white on a visual image but dim in infrared, the meteorologist can conclude that the clouds are very thick but very low, which indicates fog. If an area is bright white on a visual image and on infrared, the cloud is very thick but also reaches high into the atmosphere, which is indicative of the high tower of clouds that often result in thunder storms.