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Why does hail appear in summer? What are the prediction methods of Hail in summer?

In summer, many areas suffered from rainstorm and hail, and vegetable greenhouses and field crops were seriously affected. Do you know why there is hail only in summer? Let's take a look at the reasons why hail appears in summer carefully arranged by Xiaobian. If the morning of hail season is cool, the humidity is high, and the solar radiation is strong at noon, resulting in strong air convection, it is easy to develop into cumulonimbus and form hail.

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The reason why hail appears in summer

In the hail cloud, the strong updraft carries many large and small water droplets and ice crystals moving, some of which are combined with ice crystals to freeze into larger ice particles. These particles and supercooled water droplets are transported to the water content accumulation area by updraft, and can become the core of hail. The initial growth core of hail has good growth conditions in the water content accumulation area.

After hailstones are carried into the growing area by updraft, they collide with supercooled water droplets in the area with large amount of water and not too low temperature, and grow into a transparent ice layer. Then they enter the low temperature area with small amount of water, which is mainly composed of ice crystals, snowflakes and a small amount of supercooled water droplets.

At this time, the hail has grown up, and the updraft is weak there. When it can not support the growing hail, the hail will fall in the updraft. In the falling process, it will continue to grow by merging ice crystals, snowflakes and water droplets. When it falls into the higher temperature area, the supercooled water droplets will form a transparent ice layer.

At this time, if it falls into another stronger updraft area, the hail will rise again and repeat the above growth process. In this way, the hail grows transparently in one layer, and the thickness and other characteristics of each layer are different due to the difference of growth time, water content and other conditions. Finally, when the updraft cannot support the hail, it falls from the clouds and becomes the hail we see.

When the raindrops in the cloud meet the strong rising air flow and are brought to the altitude below 0 ℃, they will liquefy into small ice beads; when the air flow weakens, the small ice beads will fall back; when the rising air flow with water vapor increases again, the small ice beads will rise and increase again; if they soar up and down in this way, the small ice beads may gradually become big hail and finally fall to the ground.

Prediction method of Hail in summer

Feeling cold and hot

If the morning of hail season is cool, the humidity is high, and the solar radiation is strong at noon, resulting in strong air convection, it is easy to develop into cumulonimbus and form hail. It is said that it is chilly in the morning, and it breaks its head in the afternoon, and that the dew is heavy in the morning, and then the hail is fierce.

Distinguish the wind direction

Strong wind often appears before hail, but the wind direction changes strongly. There are some agricultural proverbs, such as "evil clouds see long wind, hail falls with the wind", "wind twists the clouds, hail flakes" and so on. In addition, if the wind direction changes to northwest or north wind after continuous south wind blowing, and the wind increases, hail often comes with it. Therefore, there is a saying that "no east wind, no rain, no south wind, no hail".

Cloud observation

There are many proverbs all over the world that describe the precursor of hail from the color of clouds. For example, 'if you are not afraid of the black and black in the clouds, you are afraid of the black and red in the clouds, and you are most afraid of the white insects under the red and yellow clouds','black cloud tail, yellow cloud head, hail kills sheep and cattle', because the color of hail is white at the top and black at the bottom, then red in the middle, forming white, black and red twisted cloud filaments, and yellow at the edge of the cloud. From the statement that the cloud shape is a precursor of hail, there are 'black clouds rolling into a group in the afternoon, wind, rain and hail coming together','yellow, sultry, dark clouds turning over, Tianhe water roaring to prevent hail 'and so on, which shows that at that time, the air convection was very strong, the cloud developed rapidly, and it seemed that the thick smoke was rushing straight up, the clouds were rolling up and down, and it was very easy to hail.

Listen to the thunder

The thunder was dull. Continuous, the masses call this kind of thunder "La Mo Lei". So there's a saying that "it's OK to ring thunder, but it's OK to sulk thunder.". This is because the frequency of horizontal flash is higher than that of vertical flash in hail cloud, and the range is wide. The thunder and echo from each part of lightning are mixed together, which sounds continuous.

Know the lightning

Most of the lightning in hail clouds is the lightning between clouds, which means that the process of Hail Formation in clouds is very severe. Therefore, there is a saying that the vertical flash can prevent hail disaster.

Look at things

There are a lot of experiences in hailstone detection in different places. For example, there are proverbs in Guizhou, such as' wild geese fly low, hail comes in a hurry ',' willow leaves turn over, hail falls in the sky ',' cattle and sheep don't lie on the beam at noon, hail should be on guard in the afternoon ',' white beads come from grass heart, hail falls steadily 'and so on. We should pay attention to the above experience. Generally speaking, we should not make a decision based on a single article, but need to comprehensively analyze and apply it.