You will only see what you are able to see. When the sun goes down, these images are no longer available. Forecasters can easily identify areas of developing clouds. For example on a sunny summer afternoon, the forecaster can watch small cumulus clouds develop over the Cascades. If atmospheric conditions are right, these small cumulus may develop into thunderstorms.
Visible imagery becomes an important tool for identifying areas of fog and low clouds.
The forecaster can infer the tops of the cloud deck since the clouds will have a sharp edge where they meet the mountains. Infrared Satellite Imagery allows the forecaster to see the clouds when the sun goes down for the day. Essentially, the satellite is sensing heat. Different shades are assigned to the various temperature ranges. Some computers create enhanced images, which displays colors for certain temperature ranges.