What is frozen soil?

People living in the north have this experience. In winter, the temperature drops below zero. If you dig outdoors, you will find that the originally soft land becomes very hard, and often only a white spot is left with a shovel. Careful people will find some small ice crystals in the hard soil. If you are not discouraged, keep digging, and you will find that the hard soil is not very thick, but it is still soft under it. This layer of soil containing ice crystals is frozen soil.

Why is this happening?

Because the soil contains more or less water, when the temperature drops to zero or below, the water in the soil will condense into ice to freeze the soil, thus producing frozen soil. But why do we see only one layer of frozen soil, but not all of it? It turns out that the earth under our feet has a very special property, that is, the surface temperature decreases with the increase of depth, but at a certain depth, its temperature no longer decreases, but maintains a basically constant temperature all the year round. Scientists call this layer a constant temperature layer, and the temperature rises gradually as it gets closer to the center of the earth.

In this way, we know that frozen soil is a special kind of soil, and there is ice below zero degrees Celsius. So frozen soil is different from loess, black soil and red soil. It is a kind of frozen soil, which can be frozen black soil or frozen loess. Of course, there is less frozen red soil, because red soil is mostly developed in the south, and there are not many times when the temperature in the south is below zero.

The frozen soil we just mentioned is just a kind of frozen soil, and it will melt when the weather gets warmer. We call this kind of frozen soil seasonal frozen soil. In addition, there is a kind of frozen soil that can last for many years in some places, such as the Arctic or the Qinghai-Tibet Plateau. Because the temperature there is below zero all the year round, the frozen soil will always be frozen soil, and even in warmer years, it will only melt a small layer of the surface.

The existence of frozen soil is mainly affected by temperature. The higher the latitude, the lower the temperature. Due to the small land area in the southern hemisphere, frozen soil is mainly distributed in Eurasia and northern North America. At the same time, we also know that the higher the altitude, the lower the temperature. On some high mountains, the temperature there is below zero all the year round. Therefore, there are also frozen soils in alpine plateaus at middle and low latitudes, such as the Andes in the United States, Kilimanjaro in Africa and the Qinghai-Tibet Plateau in China.

Frozen soil on the Qinghai-Tibet Plateau

Human activities are mostly concentrated in warm areas or low-altitude plains, and we don't know much about frozen soil. However, with the expansion of human activity space and the increasing demand for resources, human beings gradually turn their eyes to space, ocean and cold polar regions. For example, in the past 40 to 50 years, the United States, Britain, Canada and other countries have stepped up the development of oil and natural gas in the Arctic and the Arctic offshore to solve the energy crisis. However, cold areas including frozen soil have their unique environmental characteristics. It is a very fragile environmental system, and once it is destroyed, it cannot be restored.

Engels said, "We should not be too intoxicated with our victory over nature. Every time such a victory, nature is retaliating against us. " The development of nature must be based on understanding and observing the laws of natural development. Only in this way can we leave a scar-free earth for people living in cold areas and future generations!

Distribution of Frozen Soil in China

The frozen soil in China is divided into high latitude frozen soil and high altitude frozen soil. High-latitude permafrost is mainly distributed in Daxing 'an Mountains, covering an area of 380,000-390,000 square kilometers. High-latitude frozen soil is the southern edge of Eurasia frozen soil, and its plane distribution obeys the law of latitude zonality, that is, the frozen soil area reaches about 100% at high altitude, and its thickness becomes thicker.

High-altitude permafrost is distributed in the Qinghai-Tibet Plateau, Altai Mountain, Tianshan Mountain, Qilian Mountain, Hengduan Mountain, Himalayas, and some eastern mountainous areas, such as Changbai Mountain, Huanggang Liangshan Mountain, Wutai Mountain and Taibai Mountain. The formation and existence of high-altitude frozen soil are controlled by local altitude.

Distribution of frozen soil in the world

Now let's do a survey from south to north to understand the development of frozen soil. We started from Nenjiang, a city in the north of Songnen Plain in China, and made observations while walking north. In Nenjiang, we will find many permafrost regions, which shows that we have reached the southern boundary of permafrost. When we continue northward to the northernmost part of the China Railway, we will find that the frozen soil that originally appeared in blocks has been connected together, and the thickness of frozen soil has also increased to 50-120m. Further north into the Arctic Circle, we will find that the towering old trees have disappeared, which brings us a tundra landscape. The thickness of frozen soil here has increased to 200-600 meters, and in some places it has even reached 1000 meters. Go north and you will reach the end of this trip-the coast of the Arctic Ocean. The climate here is extremely cold, and the frozen soil layer is 400-900 meters thick. It is the last place in the world where the thickness of frozen soil is 1400 meters.

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