Record-sized hail
NOAA

Of all the things that fall out of the sky on the orders of Mother Nature, hail might be the oddest duck in the meteorological pond. It isn't snow. It isn't rain. You can't ski in it, and you definitely shouldn't sing in it. So what in the … is it, then? Hail is what happens to rain when it falls up instead of down. Forming only in thunderstorms, hail occurs when storm updrafts sweep raindrops up into the much chillier parts of the atmosphere above, where they freeze.

Hailstones can bounce up and down in these updrafts like lottery ping-pong balls, in a cycle of melting and freezing that makes them grow larger with each rise to the chilly top of the storm. That's why the size of hail can vary from storm to storm. (You could, in fact, slice a hailstone in half and glimpse layers that represent each trip it made to the top of the storm clouds before it was tossed down to Earth.)

It is hail's ability to get big that makes people squeamish about it. When the updraft party ends, and it's time for the hailstones to make their kamikaze descent, that's where trouble can start. Hail can damage houses, cars, young crops and even people if the right, oversized chunk of plummeting hail hits you! According to the National Oceanic and Atmospheric Administration (NOAA), hail causes $1 billion annually in damages to property and agriculture. Small, pea-sized hail can easily harm young grains. So just imagine what the really big hailstones -- those on the order of a tennis ball or larger in size -- can do. They can come in for a landing at greater than 100 miles per hour (161 kilometers per hour), damaging much of what sits along their path.

In 2010, South Dakotans got a record-breaking look at hail in action when a July 23rd thunderstorm in the small town of Vivian produced hailstones at least as big as softballs. After the storm, one resident found a hailstone so big it prompted him to freeze it right away. The hailstone he'd stashed in his freezer was 8 inches (20 centimeters) in diameter, weighed a little less than 2 pounds (0.9 kilograms) and was 18.62 inches (47.3 centimeters) in circumference, making it the biggest hailstone in U.S. history. And that was even after a power outage had caused the hailstone to have melted a little before its measurement could be taken and later validated by the National Climatic Extremes Committee.

The next time you're hunkered down in a thunderstorm and you hear that tinny "thock thock" sound of hail beating on your roof, think happy thoughts and hope that nothing record-breaking ends up in the middle of your living room.