Lower clouds in the atmosphere are warmer, so they show up as a darker shade of grey on the infrared image. Computers can process infrared images to show temperatures of specific clouds and assign colors to different temperatures. Computers process an infrared image in color to locate and track cold, tall thunderstorm clouds across the country, day or night. An echo results when a transmitted sound or signal bounces off of an object and returns to the original transmitter. This concept is very important in the detection of rain and snow with a special tool called radar.
Radar is a radio transmitter that snds out a signal which bounces off of rain and snow.
The radar signal is transmitted by a rotation dish antenna mounted on a tower. As the dish rotates in all directons, it sends signals that quickly bounce off of precipitation within a cloud. It doesn t take long for an echo to return to the radar dish. The meteorologist can track the storm on the radar scope to determine how a storm is moving. The line sweeping around the radar screen represents the radar antenna rotating in all directions.