A cloud climatology describes the time-averaged geographical distribution of cloud properties and their diurnal, seasonal, and interannual variations. Visible and infrared radiation measurements from space are used to obtain cloud top height, cloud optical thickness, and droplet sizes. Visual reports from surface observers on land and sea are used to obtain the frequency of occurrence and the amount of sky covered by each of the various cloud types such as cumulus, stratus, and cirrus. This article summarizes results from both analyses, emphasizing the half-century period of record available from the surface-based climatology.