This document discusses albedo, which is a measure of how much solar radiation is reflected by a surface. It begins by defining albedo and noting how it varies with factors like sun angle and snow grain size. It explains that small changes in albedo can have large impacts on the climate system by altering how much solar energy is absorbed. The document then discusses methods for measuring and modeling albedo remotely using imaging spectrometers and how light-absorbing impurities affect snow albedo.