Mount Everest is closer to the sun. Why is the peak temperature so low?

Mount Qomolangma is the highest peak in the Himalayas and the highest peak in the world, and half of it is located on the Qinghai-Tibet Plateau in China. At present, it is recognized that the height of the rock surface of the mountain peak is 8844 meters, and the height including snow is 8848 meters. Many climbers are proud of climbing Mount Everest.

Mount Everest is covered with ice and snow all year round, and the average annual temperature is around MINUS 30 degrees Celsius. The reason why Mount Everest can be covered with snow all year round is that the average temperature is very low. Mount Everest is obviously closer to the sun. Why is the temperature on the mountain so low? Scientific exploration bacteria will talk to you about this interesting topic.

The formation of Mount Everest

The interior of the earth can be divided into three layers: the core, the mantle and the crust. The earth's surface has been moving slowly, and the crust can be divided into six plates according to related characteristics. The Asia-Europe plate and the Indian Ocean plate pressed against each other, forming the Himalayas and the Qinghai-Tibet Plateau, with the whole Himalayan mountain as high as six or seven kilometers. Mount Qomolangma was also formed by the slow uplift under the compression of two plates.

Mount Everest is more than 8000 meters high. Once as high as tens of thousands of meters, it may be able to return to this height in the future. Interestingly, the peaks on the earth also have height restrictions, and the resistance that prevents them from continuing to grow is gravity and the bearing capacity of rocks. With the increase of mountain height, the pressure on the bottom rock is also increasing. When it exceeds the limit that the rock can bear, the rock at the bottom will melt into magma and disintegrate. Theoretical calculation shows that the highest mountain on the earth can't exceed 20000 meters.

There are also snow-capped mountains near the equator

Mount Everest is located in the north temperate zone, and its peak is covered with snow about several meters thick. Because of the high altitude, the air at the top of the mountain is very thin, and the atmospheric pressure is only 1/3 of the surface, so the water content in the air is also very low. The snow on Mount Everest is accumulated over the years.

The highest temperature of Mount Everest in summer is still below 0 degrees, and the snow will not melt. The height of snow line on the south slope is lower than that on the north slope. This is because the south slope is located on the windward side, and the warm and humid airflow from the Indian Ocean is relatively cold, resulting in more snowfall, and the precipitation on the south slope is richer than that on the north slope.

In addition to temperate mountains, there are also snow on high-altitude peaks near the tropical equator, such as the peak of Kilimanjaro (located in Kenya, Africa) near the equator.

The picture above shows Mount Kilimanjaro near the equator.

This is because near the surface of the earth, strictly speaking, it should be the troposphere of the atmosphere. Every time the altitude rises 100 meters, the temperature drops by about 0.6 degrees Celsius. According to climbers' measurements, the lowest temperature of Mount Everest can reach MINUS 50 degrees Celsius, slightly higher than the theoretical value.

Why is the temperature lower as you get closer to the sun?

In our daily experience, the stronger the solar radiation, the higher the ambient temperature. Closer to the sun (high altitude) and direct sunlight (low latitude), the temperature should be higher, but there is snow in the mountains near the equator. In fact, there is snow all the year round in mountainous areas above 5 kilometers above sea level all over the world. Why the higher the altitude, the lower the temperature?

In fact, the temperature decreases with the elevation, which only applies to the troposphere. The atmospheric temperature in the stratosphere will gradually increase with the elevation.

Troposphere is the layer closest to the ground in the earth's atmosphere, accounting for 75% of the total mass of the whole earth's atmosphere. 90% of the water vapor in the earth's atmosphere is concentrated in the troposphere, which means that almost all clouds are located in the troposphere. The height of the tropopause from sea level gradually decreases with the increase of latitude, ranging from 1.7 m to 1.8 m in low latitudes, from 1 m to 1.2 m in mid latitudes, and only 8,000 m to 9,000 m in polar regions.

When the sun shines on the earth's surface through the atmosphere, it will warm the earth's surface, and the ground will radiate heat to the atmosphere in the form of long waves (invisible infrared rays). Under the action of the earth's gravity, the atmospheric density presents a gradient distribution, and the surface temperature naturally presents a gradient distribution. The higher the altitude, the lower the atmospheric density and the lower the temperature.

The surface air receives more and denser ground radiation, and the natural temperature is higher. There is snow all the year round at high altitude, and the reflectivity of snow to solar light is very high, which makes the surface absorb less sunlight, and the temperature is naturally much lower than that near sea level.

Some people may think it is a joke that Mount Everest is closer to the sun. Taking the Qinghai-Tibet Plateau in China as an example, the solar radiation received in this area is much stronger than that in other parts of the country, mainly because of its low latitude, high altitude and thin air. During the day, the solar radiation is strong and the temperature is very high; At night, due to the thin air and poor thermal insulation, it will become extremely cold. Tibetan robes are related to the large temperature difference between day and night in plateau areas.

Vertical distribution of atmospheric temperature

Speaking of troposphere, let's introduce the stratification phenomenon of the atmosphere. The earth's atmosphere can be divided into five layers, from inside to outside: troposphere, stratosphere, mesosphere, thermosphere (also called warm layer) and exosphere (also called outer layer). The space outside the atmosphere belongs to interstellar space, which is completely in a vacuum state and has no temperature.

The average temperature of the earth's surface is about 15 degrees Celsius. From the above figure, it can be found that in the troposphere and mesosphere, the temperature will gradually decrease with the elevation; Above the stratosphere and warm layer, the temperature will gradually increase with the elevation. It can be seen that the temperature of the atmosphere does not decrease gradually with the increase of height, and the temperature of the outer atmosphere will be hot.

The reason for this phenomenon is atmospheric stratification. The earth's atmosphere is mainly composed of nitrogen, oxygen, carbon dioxide and water vapor. Their densities are different, and their absorption capacity for various electromagnetic radiation is also different. For example, carbon dioxide is an important greenhouse gas, its density is higher than the average density of air, and it is usually located at the bottom of the atmosphere.

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It can be seen that the temperature on Mount Everest is very low, because the upper atmosphere is thin, which is much worse than the heat preservation effect of the surface atmosphere, and there is less long-wave radiation on the ground. So at an altitude of more than 8000 meters, even in summer, the snow will not melt.