Large hailstones falling at speeds exceeding 100 kilometers per hour highlighted the dangers of severe weather after unstable conditions brought heavy rain and hail to parts of eastern and northern Japan on June 12th, with experts warning that hailstorms can now occur at any time of year and are becoming increasingly difficult to predict.
Hail forms inside thunderclouds, beginning as tiny ice crystals. As these crystals collide with and collect supercooled water droplets within the cloud, they gradually grow larger. Powerful updrafts repeatedly carry the developing ice particles upward, allowing additional layers of ice to accumulate. Through this cycle, the ice continues to grow until it eventually becomes too heavy to remain suspended and falls to the ground.
The distinction between hail and graupel is generally based on size. Ice particles measuring less than 5 millimeters in diameter are classified as graupel, while those measuring 5 millimeters or more are considered hail.
Large hailstones can cause significant damage. Vehicles may be dented or have windows shattered, while people struck directly can suffer serious injuries. According to weather experts, hailstones measuring around 50 millimeters in diameter can reach falling speeds of more than 100 kilometers per hour. The impact is comparable to dropping a golf ball from roughly the height of a 10-story building.
Meteorologists advise people to be alert for warning signs that often precede a hailstorm. A sudden darkening of the sky, frequent lightning, and rapidly deteriorating weather conditions can indicate that hail is imminent.
Anyone caught outdoors when hail begins to fall should seek shelter inside a sturdy building as quickly as possible. If immediate shelter is unavailable, experts recommend using a bag or other object to protect the head while moving to safety. People are also urged not to venture outside to observe the storm, as injuries can occur even after hail has begun falling.
Weather forecasters continue to encourage the public to monitor the latest weather information and severe weather alerts, particularly during periods of unstable atmospheric conditions.
Source: ウェザーニュース
