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Taken together, visible and infrared satellite imagery conveys a lot of information about the clouds which appear in them. One obvious bit of information is the structure of the clouds. Broad, featureless clouds are stratiform, and may be cirrus, altostratus, or stratus. Rounder, smaller, textured clouds tend to be convective, such as cumulus or cumulonimbus.
Another bit of information is the height of the clouds. In the infrared image, high clouds appear bright, while low clouds appear dark. Very low clouds may be very difficult to see in an infrared image and you may need to check a visible satellite image to distinguish very low clouds from the underlying land surface.
A third bit of information is the thickness of the clouds. In the visible satellite imagery, thick clouds show up as a bright white, while thinner clouds are more difficult to detect.
Let's take another look at the cloud patterns over the East Coast, in the visible and infrared satellite images. The clouds in the southern portion of the images appear to be convective. Notice how much more structure is apparent in the visible image, even though the resolution of the visible image has been cut in half for display purposes. You can tell that they are low because the are warm: in the infrared image their temperature can be seen to be comparable to the temperature of the sea surface farther north. The wind direction is from the north, so it appears that these clouds are caused by air passing over the Gulf Stream, picking up heat and moisture, and becoming unstable. First tiny cumulus clouds form; these clouds eventually merge together to form larger cells.
The other type of cloud visible in these images is the thin cirrus over Maryland. How do I know it's thin cirrus? I can tell it's cirrus because it shows up so bright in the infrared image, meaning that it must be especially cold and therefore very high in the troposphere. I can tell it's thin because it can barely be seen in the visible satellite image. In fact, it's semi-transparent.
Have another look at the visible and infrared images of North America. Take a look at the different types of clouds and compare the appearances of high clouds and low clouds.
1. The clouds over Texas are:
2. The clouds over the Gulf of Mexico which show up brightly in the IR image are:
3. The clouds off the coast of Baja California are:
4. The clouds over Lake Huron are:
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