It’s the one frozen precipitation that can occur in the middle of a summer heatwave: Hail.
Here’s a list of seven facts you may not know about those pellets of ice:
Hail requires strong updrafts commonly found in the middle of thunderstorm clouds to form. Those upward winds continuously blow raindrops to the frozen upper reaches of a thunderstorm, where it will turn into a hailstone.
It will then begin to fall, collecting new raindrops on the way down until it reencounters those updrafts, and it’ll blow skyward, freezing this newly acquired water into another layer of ice.
The process will repeat, and the hailstone will continue to grow in size until it is heavier than the updraft can support, then it will fall to the ground.
According to the National Weather Service, upward wind speeds of 64 mph will support a hailstone as large as a golf ball, while a grapefruit-sized stone needs a 98-mph updraft.
Golf ball- to softball-sized hail can fall at speeds ranging from 44 to 72 mph, according to the National Weather Service, while larger stones can reach 100 mph.
The largest hailstone recorded in the U.S. was 8 inches in diameter and 18.62 inches in circumference, found in Vivian, South Dakota, in 2010. It weighed nearly 2 pounds.
For comparison, a volleyball is also about 8 inches in diameter.
As you might imagine, getting pelted with millions of ice balls ranging in size from golf balls to grapefruits can cause some damage. From pummeling crops to blistering siding of homes:
…and shattering windows, to leaving its mark (several times over) on vehicles that were outside.
All told, large hail causes an average of $1 billion in damage to property and crops in the U.S. each year.
Central Oklahoma has reported the most 1-inch-plus hail events in the U.S. since 2015, with over 2,200. Rapid City, South Dakota, is second with 1853, while the northern Texas region was third at 1695.
Meanwhile, the San Francisco area hasn’t had any reports of a such-sized hail event since at least 2015, while Seattle and Western Washington have had just one report.