Infrared Water Vapor 11 a.m. Visual Infrared Water Vapor 11 p.m. Infrared Water Vapor Interpreting the Images Visual Images Visual images are created by light reflected off of the earth's surface, clouds, fog, and snow. Brighter areas indicate snow cover or thunderstorms. Areas not as light show fog or thin clouds.
Visual images are available for each hour only during daylight hours.
Movement of clouds and fronts can be seen by looking at several consecutive hours of visual images. Wind direction can also be determined this way. Images vary in size, from 40 to 180K, depending on the time of day and the amount of cloud cover. Infrared Images Infrared images are created by the amount of radiation emitted from the earth's surface, clouds, fog, and snow. Brightness on these maps is directly related to temperature.