How was Dewanda Lake in Antarctica formed?

Scientists have two views on this strange phenomenon: some people think it is caused by solar radiation. That is to say, in the summer in Antarctica, the sun shines for a long time, and the surface of Lake Vanda receives more solar radiation energy; Because the lake freezes in winter, the salt content will increase, so the density of water will increase. In this way, even when the water temperature rises in summer, the density of surface water is relatively large, which leads to the sinking of warm surface water, thus raising the bottom water temperature. However, people who hold different opinions think that there is more sunshine in the Antarctic in summer, but the Antarctic is always gloomy in summer, and the solar radiation reaching the ground is weak. In addition, the ice surface of Fanda Lake reflects 90% of the radiation energy, so the radiation that can reach the ground will be less, and it is impossible to make the surface water temperature rise very high. If warm water sinks, the whole water temperature should rise through the heat transfer of water, and it is impossible to only raise the water temperature at the bottom. Moreover, the Antarctic polar night lasts for half a year, so it is impossible for Fanda Lake to get so much solar radiation. In this case, it is impossible to maintain such a high water temperature.

Geothermal theory

erebus volcano

Others believe that it is caused by geothermal activity. Lake Fanda is 50 kilometers from the Ross Sea. There are two volcanoes near the Ross Sea, one is "Merben Volcano" and the other is "Erebus Volcano". Merbourne volcano is an active volcano, and Mount Erebus is still erupting. It can be explained that the magmatic activity in this area is very strong, which will produce high geothermal energy. Under the influence of this high geothermal energy, the water temperature of Lake Fanda will appear the phenomenon of upper cooling and lower heating. Some people disagree with this view. They believe that there is a lot of evidence that there is no geothermal activity in the dry valley area without snow. Therefore, the view of geothermal activity is simply untenable. [ 1]

New argument

American scholar Wilson and Japanese scholar torii Tieno are also the main schools of solar radiation theory. After years of research, they put forward new arguments and won the support of more people. They believe that although the summer sunshine in Antarctica is very long, the solar radiation energy received by the ground is really pitiful due to the gloomy weather and the strong reflection of the ice. But ice is transparent to sunlight, so the ice below the surface will get more or less the energy radiated by the sun. In addition, the wind is strong, the snow is blown away by the wind in winter, and the snow layer is very thin, mostly bare rocks, which makes the ground absorb more heat in summer and the climate is warmer. Over the years, the temperature of the surface and the ice below will rise and eventually melt. Because of the high salinity and density of the bottom layer, the bottom water will not rise to the surface layer, and the result is that the characteristics of high temperature are preserved. At the same time, the surface layer loses heat in winter, and the bottom layer relies on the protection of the upper water layer, so the heat loss is less, so the water temperature at the bottom layer is extremely high. Recently, scientists have observed that the bottom water temperature is rising slowly, and found that salt solutions such as calcium chloride can effectively accumulate solar heat, which provides a favorable basis for this theory. But things are not over. Geothermal theorists believe that the above argument has many imaginary elements and is still unconvincing. For example, how much sunlight can an ice layer with a thickness of more than ten meters penetrate? What is the scientific basis for these sunlight to penetrate the ice layer and melt it, raising the water temperature to such a high level? If that's the case, there won't be only one lake like Fanda Lake, but there should be many, many. What is the actual situation? Therefore, geothermal theorists still insist on their own view that although there is no geothermal activity in the Antarctic dry valley drilling plan, the possibility of geothermal activity cannot be ruled out because of the limited number and low depth of drilling holes.