Fall of the city. Does hail happen at night: meteorological observations

When hail comes, the roof and drainpipes shake with a terrible roar, hail can cause destruction. Hailstones can pierce through the wing of an aircraft, beat wheat shoots, hail kills horses, cows and other domestic animals. In a short time, such abundant hail can fall that it completely covers the earth.

Stormy streams carry out after a strong hail of accumulation of ice up to two meters long and wide. Small hailstones are often round . They fall to the ground like little billiard balls. But it happens that the shape of the hailstones has unusual outlines: either the sun with rays, or the frozen letter “X”. The various forms are caused by the wind blowing high in the air over the resulting hailstone.

The biggest hailstone

The largest hailstone ever seen fell in September 1970 near Coffeeville, Kansas. It was more than 40 centimeters in diameter, weighed about 800 grams, and ice spikes protruded from it in different directions. This shapeless piece of ice resembled a medieval deadly weapon.

How does hail occur?

Thunderclouds are real hail factories. Powerful air currents carry dust, sand and other small particles inside a thundercloud. A hailstone is formed when pieces of ice stick to particles moving through the air inside the cloud. In some hailstones, such a particle may be dead insects.

Interesting:

What is the "greenhouse effect"?

The hailstone grows larger and larger, as more and more ice clings to the wind-born ice "ship", rushing without a rudder and without sails through a thundercloud. If you split a hailstone, you can trace the history of its birth. Rings are visible on the fault, like rings on a stump, marking the stages of hailstone growth. One layer is transparent, the other is milky cloudy, the next is transparent again, and so on.

Interesting fact: a hailstone weighing about 800 grams fell in 1970.

What causes the difference in the structure of hailstone layers?

When ice on a hailstone freezes quickly (at very low temperatures). To carry a hailstone with a diameter of about 10 centimeters through the air, ascending air jets in a thundercloud must have a speed of at least 200 kilometers, snowflakes and air bubbles are included in it. This layer looks cloudy. But if the temperature is higher, then the ice freezes more slowly, and the included snowflakes have time to melt, and the air escapes. Therefore, such a layer of ice is transparent. From the rings, you can trace which layers of the cloud the hailstone visited before falling to the ground.

How does a city get big?

The hailstone grows, flying up and down the cloud. During this time, it becomes harder and harder. It is clear that in order for the hailstone to become substantially heavier, the wind in the cloud must be very strong. For example, in order for a hailstone to grow to 10 centimeters in diameter, the wind speed must be at least 200 kilometers per hour. These powerful currents of air carry the hailstone until its weight becomes such that the wind can no longer support it in a suspended state. Now the hailstone is falling to the ground.

Hail is a natural phenomenon known to almost every inhabitant of the planet from personal experience, from films or from the pages of printed publications. At the same time, few people think about what such precipitation really is, how they form, whether they are dangerous for humans, animals, crops, etc. Not knowing what hail is, you can be seriously scared when you encounter such a phenomenon for the first time. So, for example, the inhabitants of the Middle Ages were so afraid of ice falling from the sky that even with indirect signs of their appearance, they began to sound the alarm, ringing bells and firing cannons!

Even now, in some countries, special crop covers are used to save the crop from heavy rainfall. Modern roofs are being developed with increased resistance to hailstone impacts, and caring car owners are sure to try to protect their vehicles from falling under “shelling”.

Is hail dangerous for nature and humans?

In fact, such precautions are far from unreasonable, because a large hail can really cause serious damage to property and the person himself. Even small pieces of ice falling from a great height acquire significant weight, and their impact on any surface is quite noticeable. Every year, such precipitation destroys up to 1% of all vegetation on the planet, and also causes serious damage to the economies of different countries. So the total amount of losses from hail is more than 1 billion dollars annually.

You should also remember how dangerous hail is for living beings. In some regions, the weight of falling ice floes is sufficient to injure or even kill an animal or person. Cases have been recorded when hailstones pierced the roofs of cars and buses and even the roofs of houses.

In order to determine the degree of danger of ice and respond in time to a natural disaster, one should study hail as a natural phenomenon in more detail, as well as take basic precautions.

Grad: what is it?

Hail is a type of rainfall that occurs in rain clouds. Ice floes can form in the form of round balls or have jagged edges. Most often these are white peas, dense and opaque. The hail clouds themselves are characterized by a dark gray or ashy hue with ragged white ends. The percentage probability of solid precipitation depends on the size of the cloud. With a thickness of 12 km, it is approximately 50%, but when it reaches 18 km, hail will be a must.

The size of the ice floes is unpredictable - some may look like small snowballs, while others reach several centimeters in width. The largest hail was seen in Kansas, when “peas” up to 14 cm in diameter and weighing up to 1 kg fell from the sky!

May be accompanied by hail precipitation in the form of rain, in rare cases - snow. There are also loud peals of thunder and flashes of lightning. In prone regions, severe hail may occur along with a tornado or tornado.

When and how hail occurs

Most often, hail forms in hot weather during the daytime, but in theory it can appear up to -25 degrees. It can be seen during rain or just before other precipitation. After a downpour or snowfall, hail occurs extremely rarely, and such cases are the exception rather than the rule. The duration of such precipitation is short - usually everything ends in 5-15 minutes, after which you can observe good weather and even bright sun. However, the layer of ice that has fallen out in this short period of time can reach several centimeters in thickness.

Cumulus clouds, in which hail is formed, consist of several separate clouds located at different heights. So the top ones are more than five kilometers above the ground, while others “hang” quite low, and they can be seen with the naked eye. Sometimes these clouds resemble funnels.

The danger of hail is that not only water gets inside the ice, but also small particles of sand, debris, salt, various bacteria and microorganisms, which are light enough to rise into the cloud. They are held together with the help of frozen steam and turn into large balls that can reach record sizes. Such hailstones sometimes rise several times into the atmosphere and fall back into the cloud, collecting more and more "components".

To understand how hail is formed, just look at one of the fallen hailstones in the section. In structure, it resembles an onion, in which transparent ice alternates with translucent layers. Secondly, there is various "garbage". Out of curiosity, you can count the number of such rings - that is how many times the ice rose and fell, migrating between the upper layers of the atmosphere and the rain cloud.

Causes of hail

In hot weather, hot air rises, carrying with it particles of moisture that evaporate from water bodies. In the process of lifting, they gradually cool down, and when they reach a certain height, they turn into condensate. Clouds are obtained from it, which soon rain or even a real downpour. So if there is such a simple and understandable water cycle in nature, then why does hail happen?

Hail happens because on particularly hot days, hot air flows rise to record heights, where temperatures drop well below freezing. Supercooled droplets that crossed the threshold of 5 km turn into ice, which then fall out as precipitation. At the same time, even for the formation of a small pea, more than a million microscopic particles of moisture are needed, and the speed of air flows must exceed 10 m/s. It is they who keep the hailstone inside the cloud for a long time.

As soon as the air masses are not able to support the weight of the formed ice, hailstones break down from a height. However, not all of them reach the ground. Small pieces of ice will have time to melt along the way, and fall out in the form of rain. Since quite a few factors are required to coincide, the natural phenomenon of hail is quite rare and only in certain regions.

Precipitation geography or at what latitudes hail can fall

Tropical countries, as well as inhabitants of the polar latitudes, practically do not suffer from precipitation in the form of hail. In these regions, a similar natural phenomenon can only be found in the mountains or on high plateaus. Also, hail is rarely observed over the sea or other bodies of water, since in such places there are practically no ascending air currents. However, the chance of precipitation increases as you get closer to the coast.

Usually hail falls in temperate latitudes, while here it “chooses” lowlands, and not mountains, as is the case with tropical countries. There are even certain lowlands in such regions, which are used to study this natural phenomenon, since it occurs there with enviable frequency.

If, nevertheless, precipitation finds an outlet in rocky terrain in temperate latitudes, then they acquire the scale of a natural disaster. Ice floes are formed especially large and fly from a great height (more than 150 km). The fact is that in especially hot weather, the relief warms up unevenly, which leads to the emergence of very powerful updrafts. So drops of moisture rise along with air masses for 8-10 km, where they turn into hailstones of a record size.

They know firsthand what a city is, the inhabitants of North India. During the summer monsoons, ice up to 3 cm in diameter often falls from the sky, but larger-scale precipitation also occurs, which cause serious inconvenience to the local natives.

At the end of the 19th century, such a strong hail passed through India that more than 200 people died from its blows. Ice precipitation is also causing serious damage to the American economy. Heavy hail falls almost throughout the country, which destroys crops, breaks the road surface and even destroys some buildings.

How to escape from a large hail: precautions

It is important to remember, having met hail on the road, that this is a dangerous and unpredictable natural phenomenon that can pose a serious threat to life and health. Even small peas, falling on the skin, can leave bruises and abrasions, and if a large ice floe hits the head, a person may well lose consciousness or get seriously injured.

At the beginning, the ice may be a little smaller, and during this time, you should find a suitable shelter. So, if you are in a vehicle, do not go outside. Try to find a parking garage, or stop under a bridge. If this is not possible, park the car at the curb and move away from the windows. With sufficient dimensions of your vehicle - lie on the floor. For safety reasons, cover your head and exposed skin with a jacket or blanket, or at least cover your eyes with your hands as a last resort.

If during rainfall you find yourself in an open area, urgently find a reliable shelter. At the same time, it is categorically not recommended to use trees for this purpose. Not only can they be struck by lightning, which is a constant companion of hail, but ice balls can also break branches. Injuries received from chips and branches are no better than bruises from hailstones. In the absence of any canopy, just cover your head with improvised material - a board, a plastic cover, a piece of metal. In extreme cases, a tight denim or leather jacket is suitable. You can fold it in several layers.

It is much easier to hide from hail indoors, but with a large diameter of ice, precautions should still be taken. Turn off all electrical appliances by pulling the plugs out of sockets, move away from windows or glass doors.

Spherical or irregularly shaped (hailstones) ranging in size from a millimeter to several centimeters. There are hailstones measuring 130 mm and weighing about 1 kg. Hailstones consist of a series of layers of transparent ice at least 1 mm thick, alternating with translucent layers.

Hailstone with a diameter of about 60 mm

The hail layer is sometimes several centimeters thick. The duration of the fallout is from several minutes to half an hour, most often 5-10 minutes and very rarely - about 1 hour.

hail formation

Hailstone nuclei are formed in a supercooled cloud due to the random freezing of individual droplets. In the future, such nuclei can grow to a significant size due to the freezing of supercooled drops colliding with them, as well as the freezing of hailstones between themselves. Large hailstones can appear only if there are strong updrafts in the clouds that can keep them from falling to the ground for a long time.

Damage and hail control

Hail causes great damage to agriculture, destroys crops and vineyards.

Even in ancient times (at least in the Middle Ages), people noticed that a loud sound prevents hail or causes smaller hailstones to appear. Therefore, bells were rung and/or cannons were fired to save the crops.

Literature

• // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
• Geneva R. Grad. Translation from French, L., 1966

see also

• shower snow
• Heavy rain with snow

Links

Wikimedia Foundation. 2010 .

See what "Grad" is in other dictionaries:

hail- hail, and ... Russian spelling dictionary

Explanatory Dictionary of Ushakov

1. GRAD1, city, husband. 1. One of the types of precipitation falling in small ice balls. The hail has destroyed the crops. It was raining with hail. Hail the size of a walnut. 2. trans., only units. Many (about something showering, striking; bookish). City ... ... Explanatory Dictionary of Ushakov

1. GRAD1, city, husband. 1. One of the types of precipitation falling in small ice balls. The hail has destroyed the crops. It was raining with hail. Hail the size of a walnut. 2. trans., only units. Many (about something showering, striking; bookish). City ... ... Explanatory Dictionary of Ushakov

1. GRAD1, city, husband. 1. One of the types of precipitation falling in small ice balls. The hail has destroyed the crops. It was raining with hail. Hail the size of a walnut. 2. trans., only units. Many (about something showering, striking; bookish). City ... ... Explanatory Dictionary of Ushakov

1. GRAD1, city, husband. 1. One of the types of precipitation falling in small ice balls. The hail has destroyed the crops. It was raining with hail. Hail the size of a walnut. 2. trans., only units. Many (about something showering, striking; bookish). City ... ... Explanatory Dictionary of Ushakov

1. GRAD1, city, husband. 1. One of the types of precipitation falling in small ice balls. The hail has destroyed the crops. It was raining with hail. Hail the size of a walnut. 2. trans., only units. Many (about something showering, striking; bookish). City ... ... Explanatory Dictionary of Ushakov

Dahl's Explanatory Dictionary

Husband. air-frozen raindrops; in the smallest form, groats. Grainy hail, ordinary, with peas; hail hazel, with Russian walnut: hail with pigeon, with chicken egg; hail and verns, not round, as if ice fragments. Hail of bullets, ... ... Dahl's Explanatory Dictionary

1. GRAD, a; m. 1. Atmospheric precipitation in the form of rounded ice floes, which are raindrops frozen in the air. Rain with hail. G. fell out. G. broke the crops. 2. what. Plenty, abundance, flow of smth. G. bullets. G. stones. G. reproaches, objections ... encyclopedic Dictionary

hail- hail: According to GOST R 22.0.03; Source … Dictionary-reference book of terms of normative and technical documentation

Books

• City of Petrov in the history of Russian culture. Textbook for universities, Kagan MS. `Grad Petrov` the first experience of a holistic consideration of the culture of St. Petersburg, the patterns of its history and its being as a unique phenomenon in the development of national culture. The author explores...

Hail is one of the most unusual and mysterious atmospheric phenomena. The nature of its occurrence is not fully understood and remains the subject of fierce scientific debate. Does hail happen at night - the answer to this question is of interest to everyone who has never seen this rare phenomenon at night.

Brief information about the city

Hail is called atmospheric rainfall in the form of pieces of ice. The shape and size of these precipitations can vary greatly:

• Diameter from 0.5 to 15 cm;
• Weight from a few grams to half a kilogram;
• The composition can also be very different: both several layers of transparent ice, and alternating transparent and opaque layers;
• The form is the most diverse - up to bizarre formations in the form of "flower buds", etc.

Hailstones easily stick together, forming large particles the size of a fist. Precipitation with a diameter of more than 2 cm in diameter is already enough to cause major damage to the economy. As soon as hail of this size is expected, a storm warning is issued.

Different states may have other size thresholds: it all depends on the specific agricultural area. For example, for vineyards, even small hailstones will be enough to destroy the entire crop.

The necessary conditions

According to modern ideas about the nature of hail, for its occurrence it is necessary:

• Water drops;
• Condensation yard;
• Updrafts of air;
• Low temperature.

A similar atmospheric phenomenon is formed in 99% of cases in temperate latitudes over large continental spaces. Most researchers believe that thunderstorm activity is a prerequisite.

In the tropical and equatorial zones, hail is a rather rare occurrence, despite the fact that thunderstorms occur quite often there. This happens because ice formation also requires a sufficiently low temperature at an altitude of approximately 11 km, which does not always happen in warm places on the globe. Hail occurs only in mountainous areas.

In addition, the probability of hail becomes vanishingly small as soon as the air temperature drops below -30 °C. Supercooled water drops in this case are located near and inside the snow clouds.

How does hail occur?

The mechanism of formation of this type of precipitation can be described as follows:

1. An ascending air flow containing a significant number of water droplets encounters a cloudy layer of low temperature on its way. It often happens that the strongest tornado acts as such an air flow. A significant part of the cloud must be below the freezing point (0 °C). The probability of hail formation increases a hundredfold when the air temperature at an altitude of 10 km is about -13 °.
2. Upon contact with the condensation nuclei, pieces of ice are formed. As a result of alternating up-and-down processes, the hailstones acquire a layered structure (transparent and white levels). If the wind blows in a direction where there are a lot of water droplets, a transparent layer is obtained. If it blows into the region of water vapor, the hailstones are covered with a crust of white ice.
3. In collisions with each other, ice can stick together and seriously grow in size, forming irregular shapes.
4. Hail formation can last for at least half an hour. As soon as the wind ceases to support the increasingly heavy thundercloud, hail will begin to fall to the earth's surface.
5. After the icicles pass the area with temperatures above 0 ° C, a slow process of their melting will begin.

Why is there no hail at night?

In order for ice particles to form in the sky of such a size that they do not have time to melt when they fall to the ground, sufficiently strong vertical air currents are needed. In turn, in order for the upward flow to be powerful enough, strong heating of the earth's surface is necessary. That is why, in the vast majority of cases, hail falls in the evening and afternoon hours.

However, nothing prevents it from falling out at night, if there is a thundercloud of sufficient size in the sky. True, at night people mostly sleep, and small hail can go completely unnoticed. That's why the illusion is created that the “freezing rain” occurs only during the day.

With regard to statistics, in most cases hail occurs in the summer at about 15:00. The possibility of its falling out is quite high up to 22:00, after which the probability of this type of precipitation tends to zero.

Observational data from meteorologists

Among the most famous cases of "freezing rain" in the dark:

• One of the most powerful night hailstorms fell on June 26, 1998 in the Illinois village of Hazel Crest. At that time, local agriculture was seriously affected by hailstones measuring 5 cm in diameter that fell around 4 o'clock in the morning;
• On September 5, 2016, hail fell in the vicinity of Yekaterinburg, which destroyed local crops;
• In the Belarusian city of Dobrusha, on the night of August 26, 2016, ice floes the size of a fist broke the windows of cars;
• On the night of September 9, 2007, hail swept across the Stavropol Territory, which damaged 15,000 private houses;
• On the night of July 1, 1991, a whole icy downpour hit Mineralnye Vody, which not only caused damage to local households, but even damaged 18 aircraft. The average size of the ice was about 2.5 cm, but there were also giant balls the size of a chicken egg.

Many people still do not know if hail happens at night. The probability of this phenomenon occurring at night is vanishingly small, but still there. Moreover, these rare cases account for many of the strongest anomalies that cause serious harm to the economy.

Hail is formed by strong updrafts of air within a large cumulus cloud. This type of precipitation consists of pieces of ice of various sizes. The hailstone structure can consist of several alternating layers of ice - transparent and translucent.

How ice floes are formed

But it also happens that it is too hot during the day, and the ascending air flow is so strong that water drops rise to a very high height, bypassing the zero isotherm region, and become supercooled. In this state, drops can occur even at a temperature of -400C at an altitude of more than 8 kilometers.

Supercooled droplets collide in the air flow with the smallest particles of sand, combustion products, bacteria and dust, which become centers of moisture crystallization. This is how an ice floe is born - all new droplets of moisture stick to these small particles and at isothermal temperature turn into a real hail. The structure of the hailstone can tell the story of its origin through layers and peculiar rings. Their number indicates how many times the hailstone rose into the upper atmosphere and descended back into the cloud.

What determines the size of hailstones

One raindrop is formed from about a million supercooled water particles. Hailstones larger than 50 mm in diameter usually form in cellular cumulus clouds where super-powerful updrafts of air are observed. A thunderstorm involving such rain clouds can generate intense wind squalls, heavy downpours and tornadoes.

How to deal with hail?

Another popular way to prevent hail is to spray fine dust artificially. For this, aircraft are usually used that fly directly over a thundercloud. When spraying microscopic dust particles, a huge number of hail nuclei are created. These tiny particles of ice intercept droplets of supercooled water. The essence of the method is that the reserves of supercooled water in a thundercloud are small, and each hail germ prevents the growth of others. Therefore, the hailstones that fall on the ground are small and do not cause serious damage. There is also a high probability that instead of hail, a regular downpour will go.

The same principle is used in the third way to prevent hail. Artificial hail nuclei can be created by introducing silver iodide, dry carbon dioxide or lead into the supercooled part of a cumulus cloud. From one gram of these substances, 1012 (trillion) ice crystals can be created.

All of these methods of dealing with hail depend on meteorological forecasts. It is important to cover young crops in time, harvest in time, hide valuables and objects, cars. Also, livestock should not be left in open areas.

Such simple measures will help to minimize the damage caused by hail. It is better to undertake them immediately, as soon as the forecast for hail was transmitted or threatening clouds of a characteristic appearance appeared on the horizon.