Take a look at the GOES 4-km infrared satellite image from Friday night/early Saturday morning. These satellite images actually show the temperature of what the satellite can detect. Colder temperatures show up lighter, warmer temperatures show up darker. So, clouds (at higher altitudes) show up light.
Temperatures are in the 30s over much of Alabama, but water temperatures in the lakes and rivers are still above 60 in most locations, so they show up as darker areas. The Tennessee River, Weiss Lake, and Lake Martin show up very well. Cool. (No, cold.)
