Scientifically explore why there are more and more sandstorms in recent years.

In some parts of northern China, there will be floating dust and sand blowing weather every spring, and the worse weather is sandstorm and strong sandstorm. The weather of floating dust, sand blowing, sandstorm and strong sandstorm is mainly distinguished by horizontal visibility. Floating dust is less than 10 km, sand blowing is between 10 km and 1 km, and sandstorm is less than 1 km. When the horizontal visibility is less than 500 meters, we call it a strong sandstorm. Sandstorm is a kind of disastrous weather, which will cause air pollution, affect traffic safety on land and in the air, make people outdoors feel uncomfortable with their eyes and respiratory system, and even cause diseases. People who have experienced sandstorms must be particularly impressed. Walking in the street, they can't open their eyes. The sand hit them in the face like handfuls of knives. The air is full of dust. Before making a sound, they will fill their mouths with sand, which makes them very painful. Wear a mask or scarf to cover your mouth when you go out, and your hair is covered with sand. The more serious consequence of sandstorm is the casualties of outdoor people or animals. So where did the dust come from?

The two biggest sources of sandstorms in China are Hexi Corridor in Gansu and Alashan League in Inner Mongolia. The desertification in these two areas is very serious, and the dust on the surface is very rich. Speaking of desertification, there are four types of desertification in China: wind erosion desertification, water erosion desertification, freeze-thaw desertification and soil salinization. Among them, wind erosion and desertification have the largest area and the widest distribution, and the two areas mentioned above belong to this type. The so-called wind erosion means that when the wind passes through dry and loose soil, it will scrape off a surface layer. This long-term process can be described as "scraping three feet." The final result of wind erosion and desertification is the formation of Gobi and desert, and a large area of quicksand is gradually produced on the ground, which is easily taken away by the wind. From April to May every year, violent atmospheric circulation activities can produce strong winds of magnitude 8 or above. For northern China, it is a common cold air transit in spring, when the wind speed can reach 25 meters per second. Such a strong wind blows the dust away from the ground and brings it to us from the remote Gobi desert area with dry climate and sparse vegetation, forming a sandstorm.