The weather in Chengdu says there will be snow and graupel this time. What is the principle?

Event Review: At 9 o'clock in the morning on February 30, 65438, many citizens in Chengdu found white spots floating in the air. Even if you can't make a snowman, even if it melts at the touch, Chengdu people say that they are already very excited. Judging from the pictures posted by netizens, most of these dots are small snow particles with no fixed shape, so it is difficult to have regular hexagons. Xiao Dixiang, chief forecaster of Sichuan Meteorological Observatory, told reporters that this phenomenon is called from meteorological standards. Hey? This is not snow. It shows that the high-altitude temperature has the conditions for snow. Many citizens recorded the flying snowflakes with their mobile phones. In order to photograph the snow, Chengdu people look for it with a flashlight and take off their clothes on the ground?

? Also known as snowball or soft hail, graupel is solid precipitation composed of white opaque ice particles, which has a snow-like structure and often bounces back when hitting hard ground, so it is brittle and fragile. In summer, in mountainous areas, there are often many supercooled water droplets frozen around the crystal nucleus, forming a white, dim round particle. Meteorology calls this kind of thing graupel, and in many places, it is popularly called Mi Xue or Snow Graupel. Generally, the diameter of graupel is between 0.3 and 2.5 mm, which is brittle and easy to break. Polonium does not belong to the category of snow, but it is also a kind of atmospheric solid precipitation.

? Speaking of graupel, many people think it is hail. The main difference between graupel and hail is that graupel is loose and hail is hard. Hail often appears in summer and autumn with strong convective activities, while graupel often appears before or falls with snow. Hail is a short-term strong convection phenomenon, and graupel is a stable phenomenon. Solid precipitation? . Visually, hail is translucent, while graupel is generally opaque. Icicles are solid precipitation composed of ice particles with snow-like structure. More than before or when it snows. Although it is rare, it is also a normal weather phenomenon. The graupel usually lands when the ground temperature is not too cold, usually before or at the same time as it snows. Colupole is produced in a strongly disturbed cloud, which is formed by the collision, freezing and merging of a large number of snow crystals (or snow masses) and Leng Yun droplets, and its descent is often in an array.

? At the same time, remind Chengdu citizens to keep warm.