What does it mean to hail in long summer?

This kind of strong convective weather generally appears in summer. In the thick and powerful cumulonimbus clouds in summer, this meteorological condition may produce hail and thunderstorms at the same time, but in most cases only thunderstorms are produced.

Rain, this is because the requirements for producing hail are more demanding. Meteorologists tell us that hail is related to the thickness of cumulonimbus clouds, the height and temperature of the atmosphere at the top of clouds, and the speed of updraft.

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If the cumulonimbus cloud is particularly thick, the upper part of the cloud is in the upper atmospheric space, where the temperature will be very low, and the small water droplets will be sent to the low temperature area above the cloud by the updraft and frozen into tiny ice particles. Even though it's falling,

In this process, it was melted due to the influence of high temperature at low altitude in summer, but it was re-frozen when it was sent to high altitude by airflow again. In this way, as long as the upper low-temperature cloud below 0℃ has enough thickness, the ice particles will freeze slightly.

When it melted, it was frozen again. Because of slow melting and fast freezing, ice particles constantly absorb water in the cloud during repeated lifting. As a result, the ice particles became bigger and bigger until the updraft couldn't stand it any longer and fell to the ground.

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According to meteorologists' calculation, the speed of updraft is about 10 m/s, which can produce thunderstorms; However, hail will only occur when the updraft speed reaches more than 20m/s, and the cumulonimbus layer is lower than.

The high-altitude part at 0℃ must also have a large thickness, so as to ensure that small water droplets or small ice particles stay in the low temperature area for enough time with the rise of airflow, enough to freeze into ice, and ensure that the melting speed is slower than freezing during repeated lifting.

Only in this way can small ice particles freeze more and more in the process of moving up and down with the airflow, and finally fall to the ground and become hail because the airflow can't hold up.

This special meteorological condition is quite rare, even in summer, it is not easy to produce in other seasons, so the chance of hail is rare, and it is mainly in summer.

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Hail disasters in China mostly occur from April to July, usually from afternoon to evening. Because of the frequent cold and warm air activities during this period, it is relatively easy to form the special meteorological conditions of hail. From the hail area of China,

Look, there are more mountains and plateaus than plains and basins; More inland, less coastal; Northeast China, Xinjiang, Tibet and the south of the middle and lower reaches of the Yangtze River are less, Yunnan, Guizhou, Inner Mongolia, Gansu, Shaanxi, Shanxi, Ningxia,

There are many places in Henan and northern Jiangsu.

Because the meteorological conditions that form hail require great stress, it is generally difficult to maintain it continuously, so the hail generally falls for a short time. Ordinary hail only lasts for a few minutes to half an hour. In addition, the area where hail falls is not too large, and it is generally distributed in a band with a width of1000-2000m.