Module O btaining a radar image is almost like taking a picture using a flashbulb. The reflected energy at a given radio wavelength depends primarily on the texture of the surface and on its electrical properties. Since it provides its own illumination of the scene, radar imaging is referred to as an active form of remote sensing.
Radar imaging uses very short radio waves, in the electromagnetic spectrum .
These waves can pass through some things, like clouds and dry desert sand, that block visible light. Radar has been used to obtain images in tropical areas where continual cloud cover makes visible light imaging difficult. Radar was also used in the discovery in North Africa of ancient buried riverbeds that once held flowing water. The process of radar imaging produces information that scientists can use to create three-dimensional models of land surfaces. Radio waves, like all electromagnetic radiation, always travel at the speed of light.