What is hail?

What is the difference between hail and snow?

Similarities: they are all solid,

Difference: the density is different. Hail is ice, of course, not as strong as the ice in the river, and the time of occurrence is not fixed; The density of snow is so small that the wind can blow.

It's hard to say what the harm is. For example, when the fruit tree planting area encounters hail, it will be miserable, and the fruit will be damaged, resulting in the loss of the factory. There are a lot of news about the closure of mountains and roads by heavy snow, especially in Xinjiang, because there are also many news about human and animal casualties caused by heavy snow.

What caused the hail?

Hail usually occurs in strong convective weather. When strong air meets strong hot and humid air (accompanied by a lot of water vapor), the water vapor condenses into ice quickly when it is cold. In the process of falling, more water vapor will condense at first, making the ice bigger. After falling out of the clouds, the hot air below is not enough to melt the ice and fall to the ground to form hail.

Hope to adopt

What is hail?

Hail mostly comes from strong convective cumulonimbus clouds. The diameter of hail is generally in the range of 5-50 mm, which can reach several centimeters to several tens of centimeters. It is conceivable that even if a small hail can exist in the cloud, it needs a strong updraft. According to statistics, the rising speed of hail must be greater than 20m/s, and it needs to be greater than 20m/s to produce hail with a diameter of 10cm. Therefore, it is possible to hail when the cloud top near the tropopause develops. When the airflow rises above 0℃, the hail is not produced immediately, and an opaque core can be seen by dissecting the hail. The outside is alternately surrounded by transparent and opaque ice. So hail is white from a distance, not as transparent as ice. Why is hail such a structure? This is determined by the process of hail formation. Because the temperature below 0℃ in cumulonimbus clouds is water droplets, and supercooled water droplets, ice crystals and snowflakes are above them. When supercooled water droplets rise with the updraft, they freeze with ice crystals or snowflakes to form the core of hail. Because the freezing time is short and the freezing speed is fast, the hail nuclei formed are mixed with air, and the organization is loose, forming an opaque white ice layer. The faster it freezes, the whiter and more opaque it becomes. After the hail core is formed, it will drop because of its heavy weight or weakened updraft. When the temperature drops below 0℃, the ice on the surface of the hail core will melt into water, and at the same time it will collide with some raindrops, and some water will stick outside. When the hail core covered by water meets a strong updraft, it is brought above 0℃ again. At this time, the water outside the hail core freezes into ice again, and then gradually freezes, so it becomes a transparent ice layer. When hail meets supercooled water droplets again, it condenses on them and collides with ice crystals and snowflakes to form opaque ice layers. The volume of hail increases and decreases, and if it is repeated many times, it may form large hail, mostly from strong convective cumulonimbus clouds. The diameter of hail is generally in the range of 5-50 mm, which can reach several centimeters to several tens of centimeters. It is conceivable that even if a small hail can exist in the cloud, it needs a strong updraft. According to statistics, the rising speed of hail must be greater than 20m/s, and it needs to be greater than 20m/s to produce hail with a diameter of 10cm. Therefore, it is possible to hail when the cloud top near the tropopause develops. When the airflow rises above 0℃, the hail is not produced immediately, and an opaque core can be seen by dissecting the hail. The outside is alternately surrounded by transparent and opaque ice. So hail is white from a distance, not as transparent as ice. Why is hail such a structure? This is determined by the process of hail formation. Because the temperature below 0℃ in cumulonimbus clouds is water droplets, and supercooled water droplets, ice crystals and snowflakes are above them. When supercooled water droplets rise with the updraft, they freeze with ice crystals or snowflakes to form the core of hail. Because the freezing time is short and the freezing speed is fast, the hail nuclei formed are mixed with air, and the organization is loose, forming an opaque white ice layer. The faster it freezes, the whiter and more opaque it becomes. After the hail core is formed, it will drop because of its heavy weight or weakened updraft. When the temperature drops below 0℃, the ice on the surface of the hail core will melt into water, and at the same time it will collide with some raindrops, and some water will stick outside. When the hail core covered by water meets a strong updraft, it is brought above 0℃ again. At this time, the water outside the hail core freezes into ice again, and then gradually freezes, so it becomes a transparent ice layer. When hail meets supercooled water droplets again, it condenses on them and collides with ice crystals and snowflakes to form opaque ice layers. The volume of hail increases and decreases, and if it is repeated many times, it may form large hail, mostly from strong convective cumulonimbus clouds. The diameter of hail is generally in the range of 5-50 mm, which can reach several centimeters to several tens of centimeters. It is conceivable that even if a small hail can exist in the cloud, it needs a strong updraft. According to statistics, the rising speed of hail must be greater than 20m/s, and it needs to be greater than 20m/s to produce hail with a diameter of 10cm. Therefore, it is possible to hail when the cloud top near the tropopause develops. When the airflow rises above 0℃, the hail is not produced immediately, and an opaque core can be seen by dissecting the hail. The outside is alternately surrounded by transparent and opaque ice. So hail is white from a distance, not as transparent as ice. Why is hail such a structure? ......

What season does hail usually occur?

It is possible in spring, summer and autumn, but not in winter. Because hail is produced in convective clouds, convective weather is needed, in which there are more hail weather in mountainous areas than in plains, while there are more severe convective weather in summer, so there are more hail in summer. In winter, the ground temperature is not high, the air movement is not so intense and complicated, and there is generally no hail.

Strong convective weather refers to sudden, violent and destructive weather, often accompanied by strong convective disasters such as thunderstorms, strong winds, hail, tornadoes and local heavy rainfall. This is a disastrous weather with great destructive power. Strong convective weather occurs in small and medium-scale weather systems, and the spatial scale is small. Generally, the horizontal range is about ten kilometers to two or three hundred kilometers, and some horizontal ranges are only tens of meters to ten kilometers. Its life history is short, with obvious suddenness, about one hour to more than ten hours, and the shorter one is only a few minutes to an hour.

Advantages and disadvantages of hail

Protection knowledge of snowstorm, rainstorm and dense fog disasters

Blizzard and hail are common. Although they may not cause disasters, we should also pay attention to protecting ourselves:

The length of blizzard days, pay attention to add clothes to keep warm; We should reduce outdoor activities and avoid frostbite.

2. When it hails, you should avoid being indoors; If you are outdoors, use rain gear or other substitutes to protect your head and move it indoors as soon as possible to avoid injury.

In a short period of time, the continuous rainstorm in an area will cause the river to rise violently, overflow dams, flood farmland and villages, and destroy roads, bridges and houses. This is a flood disaster. How should we save ourselves when the flood comes?

Under the threat of flood, if there is enough time, it should be transferred to hillside, highland and other places in an organized way according to the predetermined route; In the case of being caught off guard and surrounded by floods, we should use boats, rafts, door panels, wooden beds, etc. Let the water transfer as much as possible.

2. When the flood comes too fast to move, you should immediately climb the roof, tall buildings, big trees and high walls, take temporary shelter and wait for rescue. Don't swim alone.

In the mountainous area, if it rains continuously, it is easy to have flash floods. In this case, we should pay attention to avoid crossing the river and being washed away by mountain torrents, and also pay attention to preventing landslides, rolling stones and mudslides.

4. It is found that the high-voltage tower is toppled, and the wires are drooping or broken; Stay away from danger, don't touch or get close to it to prevent electric shock.

5. After the flood, you should take medicine to prevent epidemic, do a good job in health and epidemic prevention, and avoid infectious diseases.

Prevent the danger of dense fog

A large number of water droplets or ice crystal particles are suspended in the air near the ground, which makes people's vision blurred. When the horizontal visual distance drops below 1000 meters, it is called fog. Fog can be classified into grades. When the visible distance is less than 1000m and more than 5000m, it is called light fog. When the visible distance is less than 500 meters, it is called fog; When the visible distance is less than 200 notes, it is called dense fog.

Anti-fog measures

Try not to go out. When you have to go out, wear a mask to prevent inhalation of toxic gases.

Try to exercise as little as possible in foggy days, and don't exercise in foggy days.

Pedestrians should be careful when crossing the road and see the passing vehicles clearly.

When driving a vehicle and riding a bicycle, you should slow down and obey the traffic police's command. Don't rush by car (boat) or crowd at the ferry when you stop.

How to pay attention to safety when cycling in rainy and snowy weather?

When riding a bike in rain and snow, you should also pay attention to the following points:

When riding in the rain, don't bury your head to avoid the rain.

2. When riding a bike in rainy days, you'd better wear a raincoat and poncho instead of riding a bike with an umbrella in one hand and a handle in the other.

3. When riding a bicycle in snowy days, don't inflate the bicycle tires too much, which will increase the friction with the ground and make it difficult to slip.

4. When riding a bike in snowy days, keep a large distance from the vehicles and pedestrians in front.

5. When riding a bike in snowy days, you should choose a flat road with no ice and shallow snow. Don't slam on the brakes, don't turn sharply, and turn as wide as possible.

6. Rain and snow. The road is muddy and slippery, so you should pay more attention when riding, and be prepared for emergencies at any time. The riding speed is slower than normal weather.

How to avoid a tornado?

Tornado is a very powerful cyclone, which usually occurs in spring. Tornadoes often come very quickly and suddenly, accompanied by loud noise. It is extremely destructive and can drag sand, trees, crops, even fish in the sea and goods in warehouses to the sky, posing a great threat to people's lives and property. How to effectively protect yourself when a tornado strikes?

1. When a tornado strikes, open the doors and windows to balance the indoor and outdoor air pressure to prevent the wind from blowing off the roof and knocking down the walls.

2. indoors, people should protect their heads and squat down facing the wall.

3. When encountering a tornado in the wild, you should quickly move in the opposite direction or sideways to avoid it.

When the tornado has reached your eyes, you should find low-lying terrain to get down, close your mouth and eyes, and protect your head with your hands and arms to prevent being hit by flying objects.

5. If you encounter a tornado while driving, get off and avoid it, and don't stay in the car.

How to save yourself when the flood breaks out?

In a short period of time, the continuous rainstorm in an area will cause the river to rise violently, overflow dams, flood farmland and villages, and destroy roads, bridges and houses. This is a flood disaster. How should we save ourselves when the flood comes?

The length is threatened by the flood. If you have enough time, you should go to hillsides, highlands and other places in an organized way according to the predetermined route. ......