The mystery of hail arises from its frequent occurrence from late spring to summer, leaving many puzzled. How can hail form during the sweltering heat of summer? In China, the vast geographical area leads to varying climate differences, resulting in diverse distributions of hail. The Tibetan Plateau is known for its frequent hailstorms, while the southeastern coastal regions experience them less often. Historically, hail has caused significant damage; for instance, in 1928, a hailstorm in Nebraska, USA, resulted in accumulations of up to 4.6 meters, with the largest hailstone weighing 680 grams. In 1968, a hailstone in Bihar, India, weighed an astonishing 1000 grams and tragically killed a calf.
So, how does hail form? During summer, a large amount of water vapor rises rapidly into the upper atmosphere under intense sunlight, where it cools and condenses into small ice crystals. These crystals are then tossed around by updrafts, accumulating layers of ice until they become hailstones. Hailstones vary in size; some are as small as peas, while others can be as large as eggs, and the largest can resemble bricks. Interestingly, in a hailstorm in Bowdoin, USA, in 1894, one hailstone was found to contain a turtle inside it.
Larger hailstones are even more astonishing. In 1957, a hailstone the size of a jeep was discovered in Inner Mongolia, China; in 1973, a hailstone in Huachi County, Gansu, was found to be taller than a house. The origins of these giant hailstones remain unclear. Scientists speculate that the rear part of hail clouds is attacked by dry, cold air, causing falling raindrops to freeze and thicken, forming these large, angular hailstones. However, this remains a hypothesis, and the mystery of giant hail awaits meteorologists to unravel.
