What is "scatterometer"

n. A form of radar used to measure surface winds from satellites, by detecting scattered microwave radiation

A scatterometer or diffusionmeter is a scientific instrument to measure the return of a beam of light or radar waves scattered by diffusion in a medium such as air. Diffusionmeter using visible light are found in airport or along roads to measure the horizontal visibility. Radar scattometers use radio or microwaves to determine the normalized radar cross section (sigma-0) of a surface. They are often mounted on weather satellites to find wind speed and direction, and in industries to analyze surface roughness of surfaces.