Visible satellite imagery is an important remote sensing tool for meteorologists. Visible satellite images are simply a picture from above of what is happening at or above the surface of the earth. Not only does it detect cloud cover, but you can also see fresh snow on the images as well. This example is from Thursday morning. Notice the white band across Illinois, Indiana, and Ohio. If you were to loop this image, you would notice that this white band does not move. But, just from this still image, you are able to see rivers and other surface features which indicate that you are not viewing cloud cover, but snowpack. Cloud cover CAN be seen on this image over Iowa, Missouri, Kentucky, and Tennessee.
Check out other satellite images here.