This brochure is intended to acquaint the reader with modern ideas about the processes of formation of frost, frost and ice phenomena, with their difference from other similar phenomena, to tell about the method of their observation and the great practical importance of these observations. The brochure is designed for a wide range of readers who want to have a clear idea of ​ ​ the physical essence of the observed hydrometeorological phenomena and their practical significance for the national economy. It can be used for employees of the network of observation stations and hydrometeorological service posts as an elementary manual for advanced training.