Satellite data of Mount Spurr's three eruption clouds in 1992 were extremely useful in identifying the initial clouds and tracking their movement downwind. Explosive eruptions inject enormous volumes of volcanic ash and gases into the atmosphere, where the ash is carried downwind or hundreds or thousands of kilometers and often remains airborne for days to weeks. As the ash and gas move and disperse downwind, it becomes increasingly difficult for aircraft pilots and scientists to distinguish an eruption cloud visually from weather clouds, especially at night or in poor weather. Since ash cannot yet be detected by weather radar aboard an aircraft, satellite images and pilot reports of unexpected ash encounters provide the critical information needed to keep commercial aircraft from entering an eruption cloud downwind from an erupting volcano.

Image data from several geostationary and polar orbiting satellites are now received directly at some volcano observatories or it can be accessed via computer networks. Sensors aboard these weather satellites record the amount of thermal energy in several different wavelengths emitted (or radiated) from weather and eruption clouds and the Earth's surface. Scientists use the image data from these different wavelengths in different ways to detect and track an eruption cloud.

Although it is relatively straightforward to detect eruption clouds in a thermal imagery during an eruption, it becomes more difficult as the cloud drifts hundreds or thousands of kilometers from the vent, and disperses in the atmosphere. Weather satellites used to detect volcanic clouds measure emitted energy at several different wavelengths. Scientists have developed a mathematical operation that uses data from two different thermal wavelengths to enhance the visibility of eruption clouds and and discriminate them from meteorological clouds. The images below show the results of the technique. This type of image processing can be very valuable for tracking eruption clouds in order to prevent aircraft from encountering volcanic ash.