10 things you may not know about hail

(Baonghean.vn) - Hail is one of the most dangerous natural phenomena on earth. With extremely strong storms and whirlwinds, plus the potential for damage from hailstones, houses, trees, and people are all at risk. There are many secrets hidden in hailstones that you may not know.

Ice from the hailstorm on the afternoon of April 9 was picked up by people in Mai Son commune, Tuong Duong, Nghe An and put into bowls.

1. People often think that hail will appear in winter, but in fact, summer is when hail is most likely to occur. Hail is essentially caused by instability in the air when two hot and cold air currents meet. Therefore, in summer, when there are many columns of hot, energetic air, it is easier to create thunderstorm clouds that produce hail.

2. In the largest clouds (called cumulus clouds or cumulonimbus clouds), the air at the top of the cloud is colder and the water vapor there freezes into tiny ice particles. These ice particles move down and then back up to the top of the cloud, over and over again, each time the layer of ice around the ice particles gets thicker. When they are heavy enough, they fall to the ground and form hail.

3. The condition for a cloud to be able to produce hail is that the cloud top temperature must be below -20 degrees Celsius and most of the cloud must be below freezing temperature (0 degrees Celsius). Combined with thunderstorms, it will create large hailstorms.

4. Hailstones are usually 5 – 200mm in diameter, and can be as small as a pea, as large as an egg or even as large as a grapefruit. Each hailstone can weigh up to 1kg and if several of them stick together, they can form a 4kg mass.

When we cut a hailstone in half we see ice rings.

5. Hailstones fall so fast that they do not melt before reaching the ground, even in the middle of a hot summer day. A hailstone the size of a tennis ball (about 75mm in diameter) and weighing 150 grams can fall at a speed of 160km/h. This explains why crops and homes are severely damaged after just a few minutes of hail.

6. When you cut a hailstone in half, you can see ring-like objects made of ice. Some “ice rings” are milky white, while others are transparent. The layers of “ice rings” are interwoven, and the number of layers you count is the number of times the hailstone has moved up and down on the top of the cloud.

7. In some cold climates like the UK, hail is common in winter, but this is not the type of hail we are talking about here. Locals call it Graupel. This is a soft type of hail, formed when slow-freezing water droplets combine with a layer of ice or frost to form raindrops. Soft hail is created in a similar way to snow and is not as damaging as hard hail.

Hail is a very dangerous natural phenomenon.

8. The largest hailstone recorded in the UK was in Horsham, West Sussex on 5 September 1958, weighing 142 grams.

9. Meanwhile, in the US, the largest hailstone weighed 0.88 kg and was up to 20 cm in diameter. This hailstone appeared in a hailstorm on July 23, 2010 in Vivian, South Dakota.

10. Hail not only damages property and crops but can also kill people. In 1888, nearly 250 Indians were killed by hailstorms.

Thanh Hien

(According to Huffington Post)