GOES around, comes around
If night vision can make the highway come alive after dark, a more sophisticated infrared system on a satellite called GOES can light up the entire planet, day or night. GOES, for Geostationary Operational Environmental Satellites, is a series of satellites that observe Earth in 22 infrared channels. Each channel records a specific part of the infrared band, and carries separate information about what's present -- and absent -- at that band.

Band. We're not talking some infrared Back Street Boys wannabes. Rather, bands are specific regions of the overall infrared spectrum. Infrared researchers focus on various bands within the 4 to 15 micrometer portion of the electromagnetic spectrum because they give different information. For example, water vapor molecules in the atmosphere vibrate when they absorb outgoing infrared radiation. They then emit photons with wavelengths of six to seven micrometers. Thus the water vapor detectors on GOES read at that wavelength.

Here's some best-we-could-find info on the electromagnetic spectrum.

As we've said, infrared is made by anything warmer than absolute zero. Elements and compounds have characteristic "signatures" of emissions.

Infrared radiation is also absorbed by many solids and gases, so subtraction carries information as well. It's like looking through a bedroom screen -- you can see most of the mosquitoes trying to enter your inner sanctum, but you also know that something gray and gauzy is blocking part of your view, and you figure out that it's a screen.

Translated: The visual cues from the obstruction tell you something about the nature of the obstruction. Using a similar principle, users of GOES add or subtract channels to give a clearer picture of the atmosphere and what's in it. As you can see from the images, a plume of volcanic ash turns from a gray smudge in visible light into fluorescent in the manipulated infrared images.

Out in the ozone
It's the same way with ozone, the three-atom molecules of oxygen that are a pollutant in the lower atmosphere but a life-saving shield against ultraviolet radiation higher up. Although ozone seldom appears in the middle atmosphere, the instruments on GOES can detect it when it does. That's of theoretical and possibly practical interest: the data records a mechanism that could move ozone between helpful and harmful regions, possibly leading to a better way to protect the ozone we want and eradicate the ozone we don't.

Mixing is also a sign of severe storms. "If it's strong enough to suck stratospheric ozone down, those are strong storms," says Scott Bachmeier, a research meteorologist with the Cooperative Institute for Meteorological Space Studies at the University of Wisconsin-Madison. "It's an indication of the dynamics of a storm" that would be particularly helpful for identifying storms that bring heavy snow. A strong storm with a well-defined jet stream often has a trailing edge where stratospheric air dives down into the troposphere -- the lower portion of the atmosphere. If this downward motion is strong, it's likely that the front edge of the storm is also strong, Bachmeier says.

The beauty of GOES, says Bachmeier, is its ability to peer down into the atmosphere, and obtain data from various levels. "At the top, the atmosphere is not necessarily doing the same thing as at the bottom. It helps us understand the 3-D nature of the atmospheric fluid."

As you can see, GOES also makes great images of forest fires. Here's the complete low-down on these cool satellites. Hot stuff!

I'm an astronomer. What can infrared do for me?