The second book of the six-volume book of selected works by academician V.M. Kotlyakov discusses the processes of formation and development of seasonal snow cover, features of accumulation and ablation, mass balance and glacier regime. It tells about the formation of space glaciology and the experience of researching glacier fluctuations, including dynamically unstable ones, based on aerospace information; on glaciological forecast, as well as on the resource value of snow and ice and possible ways of their use.