There are a huge number of lakes on our planet. They can differ dramatically from each other both in size, origin, and other indicators. Then what are they similar to, and what is a lake in general?
It is not so easy to give an exact definition of this concept. For example, if you say that this is a reservoir surrounded by land on all sides, then this will not be entirely correct. Since for those into which rivers flow (or flow out of them), the coastline is torn.
If we say that this is a fresh water reservoir, then what about the Dead Sea and others in which the water is salty? We can say that they have no connection with the oceans. But the famous
Maracaibo Lake, located in South America, is connected to the Caribbean Sea.
So still what is a lake? It will be most correct to say that this is a reservoir of natural origin on land. First of all, the lakes differ in size. Sometimes in the mountains you can find small ones, only a few tens of meters long, while the largest lake on Earth - the Caspian Sea - has a length of more than 1000 kilometers.
Rainwater flows into the lakes, rivers and streams flow into them, so they should be located at low points in the terrain. But this is not always respected. The South American Lake Titicaca is located at an altitude of 3812 meters above sea level.
How are they formed
To understand what a lake is, you need to find out how they arise. There are glacial reservoirs located in the troughs of the earth's surface, formed under the enormous weight of the ancient glacier. These depressions were gradually filled with melted glacial waters. Most often they are placed in large groups, have small dimensions and depths. There are many of them in Finland, Canada, Siberia.
Mountain lakes are located in alpine hollows. Sometimes it happens that such a lake arises right in front of our eyes - during mountain collapses, the riverbed is blocked and water accumulates near the dam. Usually they are short-lived, and water quickly blurs the barrier, but there are exceptions. An example is Lake Sarez in the Pamirs.
Lakes formed in faults of the earth's crust are elongated, narrow and very deep. There are many of them in Africa: Tanganyika, Nyasa and others. Such is the deepest lake in the world, Baikal.
Ponds of tectonic origin may also have a shallow depth, for example, Khmelevsky lakes, which are located in the eastern part of the Achishkho ridge. Four closed reservoirs are filled with fresh water, not a single stream flows into them and does not flow out either.
Alpine lakes filled with glacial water are only fresh. But the Dead Sea, located in the basin, is so salty that there is no life in it.
Due to the presence of a large number of impurities in some lakes, its water is not only salty, but also turbid, which gives it a different color. But most bodies of water, especially small ones, have fresh and clean water. For example, in the Leningrad region there is Lake Bezymyannoye, which is considered one of the cleanest in Russia. The reason for this is the presence of a large number of springs and keys, constantly updating and refreshing the water.
Some of the lakes regularly change their size, and on the maps their coastline is indicated conditionally. Most often it depends on the seasonal precipitation. So, Lake Chad on the African mainland may change several times during the year.