Although water in glaciers is in the firm condition, nevertheless the ice of the glaciers flows because of specific physical characteristics. But the speed of its current is insignificant, about centimeters per day. Because of small speed the rates of renewal of water in the glaciers are comparable to the rates of renewal of water in underground waters of deep horizons and are defined first of all by linear sizes of a glacier.

In glaciers temperature grows with depth and frequently reaches a point of melting at the given pressurenear the bed of the ocean. Such condition is characteristic, for example, for the greater part of the bed ice of Antarctic ice cover. But many mountain glaciers have temperature close to the point of melting during all the year. Such glaciers are called "warm". There are glaciers, which have in basic negative temperature of ice, they are "cold" glaciers. On all the glaciers and ice covers there is thawing ice on the part of a surface, and sometimes and on all surface in summer. Taking into account that on a surface of crystals of ice the most thin layer of water even is kept at rather low temperature, snow-ice congestions are considered as systems containing liquid water. But water in glaciers exists not only as a layer, quite often there are large pockets in them filled with water, channels with innerglacier waters, layers of thaw ice.