Hail so big that it can damage a car
Credit: ERZ via Wikimedia Commons

Hail is a rare atmospheric phenomenon, since for it to happen a certain set of conditions and circumstances has to be satisfied. Rain, for instance, is statistically more prone to develop, as we all see in our daily lives. To begin, we should highlight that hail will only form in cumulonimbus (a type of cloud) that are highly developed. The cumulonimbus clouds are those that are characterized by large storm clouds whose top has a flat shape. It can span up to fifteen thousand feet, and in addition to hail, they are responsible for producing storms and tornadoes.

Hail is one of the forms of precipitation and it is reached when air currents rise very violently towards the sky. Water droplets turn into ice when they ascend to the higher parts of the cloud, or at least an area of ​​the cloud where the temperature is equal to or less than 0°C (32ºF), the freezing temperature of water. Supercooled water continues in this state because of the need for a strong initial seed to initiate the crystallization process. When these water droplets in the cloud collide with other particles or frosty grains, they can easily crystallize. In the most intense storms they can produce frozen precipitation in the form of large hail especially when it is formed within strong updrafts. In this case the hail ball can stay in the atmosphere for longer, allowing for a greater capacity for growth. Little by little, the drops of water become larger and larger, until they reach a point where the weight is such that the equilibrium is broken and they cannot remain in suspension any longer (or the upward currents reduce, thus not having enough force to maintain the hail in the cloud). That's when they start falling, taking on their way the smaller drops that were below.
Hail grains consists of frozen water, semitransparent, round or rarely conical with a diameter of 2 to 5 mm. Hail stones, however, are composed of pieces of ice, whose diameter ranges from 5 to 50 mm or more, and which fall either individually or together with other pieces.

The largest hail ball

The largest hail ball fallen in the US was 20cm (8 inches) and weighed 0.88kg (1.93 pounds). It was collected in South Dakota in 2010.

Hail damages cars

Check out the video above, it is pretty impressive (and scary). If you ever find yourself in this situation, the safest is not to go out of the car and stay away from the windows.

Due to the hardness of ice when falling in the form of hail, and especially when the balls acquire significant dimensions, hail can be very harmful to cars (and people) caught in the middle of a hailstorm. It can dent the vehicle, crack and even shatter the glass of the windshield. One of the biggest problems when hail falls is that most of the cars are outdoors, even if only parked, so they will be damaged equally.

Similarly, larger hail (more than 13cm diameter) is very dangerous for planes. It affects the roofs of houses, skylights and farmed animals that have no way of finding a shelter.

Hail damages crops

This natural phenomenon, produced in summer, caused severe damage to crops that are concentrated in a small portion of the earth's surface. Here is a small summary of what are the consequences of this and how they were dealing with it in South America[1]:

"If the analysis focuses only on the damage to the vineyards, neglecting other types of crops, as well as spending on useless systems of defense against the storm, the impact on subsequent crops, speculation on the resulting damages, etc.., hail losses only in viticulture are large: more than 13% of the total annual production. With illustrative terms, we can estimate that it takes the whole year's salary of about 8,200 families."

These losses affect the financial solvency of a large number of families or even companies, and in turn affect provincial economic networks.
Several methods have been tried to fight the phenomenon or, alternatively, take shelter from its consequences. Among the former may be mentioned the anti-hail rockets or cloud seeding, which reduces the danger although it is not completely avoided. A more reliable (and effective) method is the use of anti-hail nets, consisting of metal or synthetic fabrics that cover crops without affecting their growth. Their good results are favoring the extension of this method, although due to their high cost, the method is not applicable for all producers.

Geographic distribution

It occurs worldwide, especially in mid-latitudes and in the frontal part of mountains, due to the effect of change in direction of the currents. It causes a lot of destruction in rural areas, withtotal or partial loss of crops a previously mentioned.

There are several countries where large hail occurs: are India (closer to the mountains), China, Central Europe and Southern Australia. Hailstorms are likely in the south and west of Germany, north and east of France and south and east Benelux. In the US, the point where Colorado, Nebraska and Wyoming meet is called “Hail Alley”, and is known to be one of the most frequent spots for hail to fall.

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