Ice frost is the complete icing of water bodies.
The ice regime of reservoirs is the subject of study by many scientists. Information on the freezing of rivers and other water resources in Russia and neighboring countries has been accumulating for many years. Some evidence suggests that the timing of the occurrence and opening of ice cover fluctuate. What is the name of this natural phenomenon and what is its duration, let's try to figure it out.
Ice freezing is the process of the formation of a continuous ice coating on the surface of a reservoir or watercourse. The duration of the phenomenon and the thickness of the ice layer depend on numerous factors:
- temperature indicators in the winter period;
- wind regime;
- characteristics of the reservoir;
- thickness of the snow cover.
On mountain rivers there is never a solid freeze. This is due to the speed of the flow, preventing the freezing of water. Ice formation on large water arteries takes more time than on small rivers and non-flowing bodies of water, which include lakes and ponds.
On the territory of the western part of Russia, ice formation begins in the late fall.Full constraint of most of the reservoirs is completed in the middle of the first winter month. Free of ice during this period can only be those parts of the water where there is a rapid or warm current.
The rivers located in the temperate climate zone and subtropics have a rather complicated thermal regime. These species are the water arteries of Russia and Canada. In the hot period, the mixing of water leads to the fact that their vertical temperature varies slightly. Temperature changes over the entire duration of the river depend on the direction in which the flow is directed. Least of all fluctuations in those reservoirs, the course of which has a latitudinal strike.
Rivers such as the Don, Volga and Dnieper flow from the north towards the south. Starting from the source, the water temperature gradually rises and reaches a maximum point at the mouth of the water artery. But on the rivers of the Lena, Yenisei and Ob, the direction of flow from south to north. Accordingly, the temperature indicator at the source will be significantly higher than in the area of the river mouth.
There are three phases of freezing of the reservoir:
- ice formation;
- complete encapsulation of the water surface with ice (freezing);
- autopsy (release from ice).
Duration of freeze up
How long this phenomenon lasts depends largely on the geographical location of the reservoir and the prevailing climatic conditions during the winter period. The rivers located in the western region of Russia (for example, the Volga) are ice-bound for 4-5 months, while the Siberian Lena River may be under a layer of ice for more than six months.
The duration of the freeze-up depends on the thickness and strength of the ice coating. The ice layer on large Siberian rivers can reach an average of 1.5-2.0 meters, but the water bodies of the European part of Russia freeze through no deeper than 1 m.
What is polynya?
Frequently passages and winter roads pass through the water courses. Such movement is possible when ice is formed on the rivers. This is quite dangerous, since the strength and thickness of ice on the same areas of the reservoir may be different. Often on rivers you can observe a phenomenon that is known as a polynya. What is meant by this concept?
Polynya is a non-freezing or already melted part of the water surface, which is surrounded on all sides by fixed ice.As a rule, such a phenomenon occurs in places where there are thresholds or there are thermal changes that may be caused by the discharge of industrial fluids or the release of groundwater.
Ice is a natural phenomenon in which lakes, rivers and streams are completely covered with ice. Frozen ponds attract the attention of lovers of winter fishing and entertainment. It is important to remember that ice is an unsafe place, so you should not tempt fate. If you are not sure that the thickness of the frozen layer will be able to withstand your weight, in no case do not stand on it.
The most dangerous hydrological phenomena on rivers are:
- early freezing (phenomenon having similarities with ice jams);
- the rapid movement of ice;
- detachment of coastal ice floes.
Due to melting snow and ice cover of water bodies, the risk of high water and rising groundwater levels increases, which can lead to flooding.