There is a flag cloud on the mountain.

When the weather is clear, there will always be milky white smoke clouds floating on the top of Mount Everest, which is the flag cloud of Mount Everest. Yun Qi is formed by convective cumulus clouds, and the peak wind power can be inferred from its floating position and height. If the position of the flag cloud floats upward, it means that the smaller the wind, the more inclined it is, and the stronger the wind is; If it is equal to the summit, the wind force is about nine. Therefore, Mount Everest in Yun Qi is also called the highest weather vane in the world. The concept of landmark cloud was first put forward by Chinese geographer Mr. Xu. He pointed out that at the summit of Mount Qomolangma, the cloud belt fluttering with the wind looks like a flag hanging on Mount Qomolangma from a distance, so it is called Yun Qi. He believes that when the moist airflow rising at the southern end of Mount Everest collides with a strong westerly wind, a flag cloud extending eastward will appear on the summit. The observation shows that Yun Qi is a kind of peak cloud of Mount Everest, and it is the highest weather vane in the world because it hangs on the top of the highest peak in the world and flutters with the wind. On the northern slope of Mount Qomolangma, it is more than 7000 meters above sea level, which is quite different from the underlying surface at an altitude of 1.2 meters. The former is mainly gravel surface, while the latter is mainly ice and snow surface. After sunrise, the surface temperature of the hillside is higher than the free atmospheric temperature at the same height above 7000 meters. Isobar isobar principle, the north slope is above 7000m above sea level, and it flows through the ice and snow below 7000m above sea level. Gas sublimation water vapor sublimates from the top of Mount Everest at an altitude of 7000 meters, which provides the necessary conditions for the formation of mountain top clouds. So, at what height are clouds generated? A formula for calculating cloud condensation height was summarized by predecessors, which is related to barometric layer height, air temperature and dew point temperature. According to the radiosonde data of 1945 and 1980 Rongbusi station on the north slope, the monthly average height of the 400 HPA barometric layer above the station in April was 24.0 degrees, the average temperature was 24.3 degrees, the average dew point temperature was 33.9 degrees, and the average temperature decreased by 0.9% with the height. According to these data, the cloud condensation height difference can be calculated as1364m. Together with the average height of 400 hectopascals, the average condensation height of clouds is 8846 meters, which is very close to the altitude of Mount Everest. It can be seen that before sunrise and sunset, the clouds generated near the peak of Mount Everest move with the wind, and from a distance, it is like a flag flying at the top of the highest peak in the world. The direction of the flag cloud depends on the direction of the high-altitude wind. On the contrary, before and after sunrise, because there is no sunlight, the temperature on the surface of the gravel is lower than the free atmospheric temperature at the same altitude, forming a downhill wind, and it is difficult for peaks or flag clouds to appear on Mount Everest. In the absence of clouds, it is difficult to have summit clouds or flag clouds on the summit of Mount Everest. The change of Mount Everest's flag cloud is helpful to the short-term weather forecast of Mount Everest. In other alpine areas, generally speaking, as long as there are relatively isolated peaks, under certain ground conditions and circulation conditions, flag clouds can sometimes form.