Process by which up to 25% of radiant energy from the sun is reflected or scattered away from the surface by clouds.
https://earthobservatory.nasa.gov/glossary/b/d

Energy, when hitting a target, can be scattered in many directions. The part of the energy that is scattered back in the exact direction where it came from, is "backscattered".
https://www.nrcan.gc.ca/node/9483