In the late autumn and winter, in the Jianghuai area of China, rain and snow often fall together in the cold weather, and the duration is long. Therefore, there is a weather slogan of “sleet, no break” in this area. Why is the above weather phenomenon occurring in the Jianghuai area?
China’s Jianghuai region is the passage of the cold air in the north and the warm and humid air in the north. After the fall, the cold air in the north occupies an advantage, so the chances of cold air going south are increasing. The south of the cold air often causes rainy weather. In the winter, the cold air is stronger. At this time, the temperature in the Jianghuai area is relatively low. Once there is strong cold air going down, the temperature of the ground is often lowered below 0 °C, so that the excess water vapor in the air condenses into small ice crystals. When many small ice crystals grow, they become large snowflakes. Therefore, in the Jianghuai area in winter, it is generally snow.
Sometimes the warm and humid air in the south is relatively strong, which will slow down the speed of the cold air. When the warm and cold air meets in the Jianghuai area and forms a front, the warm and humid air climbs on the front and cools and condenses into a large cloud area. If the temperature near the ground layer is above 0 °C, the small ice crystals falling from the cloud may all melt into rainwater, and the large part will melt and become wet snow. So when it landed near the ground, there was both snow and rain, which was called sleet.
Because of the strong warm and humid air, the front between the cold and warm air can stay in the Jianghuai area for a long time, the warm and humid air continuously climbs on the front surface, and the cooling condensation forms a large range of sleet, and in a short time. The weather will not change very quickly. Therefore, “sleet, not stop” is the most common weather in the Jianghuai region of China.