Why do the ups and downs of the waves often appear before thunderstorms?

Hook cloud is called "hook cloud" by the public. It is like a bunch of silk passing through the sky, with the cloud upward and a small hook at one end. Clouds are milky white and transparent. Generally, it appears before the influence of cold air in the north or low pressure at high altitude. If this cloud appears, it will rain soon. Therefore, there is a saying that "clouds hook and rain falls". Cirrocumulus, people call it "Scale Sky". It usually appears in the dark blue sky. White clouds are arranged neatly and tightly, as calm as fish scales. After they are formed, the time is very short, usually a few minutes, and many are about an hour. Its appearance shows that the trough of low pressure moves very close in this area, which is a sign of the season from sunny to rainy. Therefore, there is a saying that it will be windy if it doesn't rain.

There are countless "cotton clouds" called "cotton clouds". It often appears in the clear sky in summer, just like a messy pile of cotton, a pile of cotton that is about to explode. Clouds are different in size, because humid air is formed under extremely unstable conditions, so it is also a symbol of clouds breaking the rain. Therefore, the agricultural proverb says, "There is a cotton cloud in the sky, and there will be a thunderstorm soon." This kind of cloud is not common in the atmosphere, so the fact that "you can tell the weather by looking at the cloud" is not too bad. According to the official forecast, there will be rain in Beijing, Tianjin and Northeast China. The initiator of this rain is a cynical stone. Today, this cynical Longyan has appeared in Mongolia. Under its impetus, a pile of Lei Yun began to appear in the south of cynic Longyan. This is an important reason for the sudden change of weather in northern China.

The cynical Longyan is active in the north of China, which is easy to cause cold current thunderstorms. This kind of rain is characterized by coming and going in a hurry, which is easy to induce severe convective weather, thunderstorm and gale, hail and other disastrous weather. Today, influenced by the periphery of the cold vortex, it has begun to hail in Mentougou, Beijing. Due to the vortex activity of the cold current, June in the northeast of North China is also the most frequent period of hail activity. Liu Xiangyun is a rare cloud in the sky. Clouds appear as undulating bubbles, which are caused by violent activities of hot and cold air and usually indicate very bad extreme weather. Including thunderstorms, short-term rainfall, strong winds and hail, and even tornadoes. The situation in Hebei Province is that the arrival of Liu from Jiangda brought thunderstorms, short-term heavy rains and even hail to Beijing and Tianjin in the North China Plain!

The "real killer" who brought this bad weather is the cold air carried by the cold current. From noon today, a small vortex of cold current swept over the North China Plain, and the cold air carried by the cold current rushed to the North China Plain. The weather in that area is sunny and the temperature is high, so cold air attacks quickly, and cold water falls into a boiling oil pan, causing strong development. This is the cumulonimbus cloud. This area was shrouded by a large cloud of rivers and streams this afternoon, and the boiling at the top of the cloud meant strong updraft activity in this area. This is the chief culprit of short-term thunderstorm, gale and hail in North China Plain.