Why are there many wonders in the northwest inland?

In the inland areas of northwest China, there are endless deserts. The sand dunes are connected here, which is a sea of sand. Sometimes, when people drive camels across the desert, they can hear camel bells far away. There are also towering Kunlun Mountains and Tianshan Mountains in the northwest, and there are majestic peaks and snow peaks all year round. In addition to these landscapes, people who have been to the northwest inland can also see some peculiar geographical and cultural landscapes. For example, in some places with extremely dry climate, there are many vibrant oases. On these oases, crops such as wheat, corn and cotton are distributed in patches, and people can often see melons and fruits and vineyards. How is this oasis phenomenon formed in the desert?

It turns out that there are some high mountains in the northwest, and the top of the mountain is covered with snow all year round. Summer has come, the temperature has risen, and the snow and ice on the mountain have melted a lot and merged into rivers, nourishing the land in front of the mountain. People use this water source for farming, thus forming an oasis. In Turpan area, local farmers use a unique irrigation method, called "karez", to divert water for irrigation and cultivate grapes with good quality. There is a grape valley in Turpan, which is about 8 km long and 1 km wide. In this land, vineyards are continuous. During the harvest season, a string of green and purple grapes hung all over the garden, forming a unique landscape here. The so-called "karez" is mainly composed of long underground water diversion channels interconnected. Water flows underground, which not only reduces evaporation but also prevents pollution; More importantly, because the water in the culvert avoids direct sunlight, the water temperature is low and cool and pleasant, which is very rare in Turpan Basin, which is famous for its dry heat.

Another strange phenomenon in the inland areas of northwest China is the great temperature difference between morning and evening. Some people say that it is "wearing a fur coat early, wearing yarn at noon and eating watermelon around the stove". What's going on here? Why is the temperature difference between day and night large?

First of all, the climate in these areas is dry, mostly sunny, and there are no clouds in Wan Li. During the day, because there is no cloud to block the sun, the sun radiates more heat to the ground, so the temperature rises rapidly. At night, because there are no clouds in the sky, there is also a lack of water vapor in the air to absorb the heat from the ground, and the heat released from the ground is distributed to the space in large quantities, so the temperature drops rapidly at night and drops to the lowest point of the day before sunrise.

Secondly, there are many deserts and bare land in these areas. Under the same sunshine, the temperature of desert and bare land rises much faster than that of water surface because of their small heat capacity, which is an important reason for the high temperature in inland areas during the day. At night, the ground releases heat to cool down, and the desert and bare land cool down much faster than water because of their small heat capacity. In this way, the temperature drop in the inland areas of China is relatively large at night.

Another strange phenomenon in the northwest is that although some places are famous for their dry climate, they can also cause floods. For example, the world-famous Mogao Grottoes are located in Dunhuang, Gansu, and there is a river called Danghe in Dunhuang. This is one of the arid areas in China, with little precipitation, but in 1979, a flood occurred. There are three reasons: first, the temperature is high this summer, and there is a lot of snowmelt on the mountain. In July, the water level in the upper reaches of Danghe Reservoir, where ice and snow melted and replenished, was quite high. Second, this year, there was a southwest airflow from the Indian Ocean, which crossed the Qinghai-Tibet Plateau and moved towards Qilian Mountain, bringing a lot of rain to Dunhuang. Third, local people cherish water very much. When the water level of Danghe Reservoir crossed the warning line, they were still unwilling to open the floodgates for flood discharge. As a result, the reservoir burst its banks and Dunhuang City was quickly flooded.

Northwest China has a vast territory, and there are abundant mineral resources such as oil, natural gas, coal and nickel underground, which has great development potential. Its colorful strange landscapes and strange phenomena add to its attractive charm.