Social media users captured videos of a storm sending huge chunks of hail clattering across Colorado on Tuesday night, some as large as eggs and golf balls.
"Severe thunderstorms rapidly blossoming across the northern Denver metro as moisture works into the Centennial State," tweeted atmospheric scientist Matthew Cappucci. "This one is dropping hailstones the size of hen eggs just northeast of Boulder as it expands into Longmont."
Hail is a type of precipitation where solid pieces of ice fall to Earth, having formed inside thunderstorm clouds. Colorado is one of the states that experiences the most hailstorms, along with Nebraska and Wyoming, according to the National Oceanic and Atmospheric Administration (NOAA). At the intersection between these three states, there is an average of 7 to 9 hail days per year.
Stock image of a large hailstone in someone's palm. Huge golfball-sized hail was seen falling across Colorado on May 9, 2023.Stock image of a large hailstone in someone's palm. Huge golfball-sized hail was seen falling across Colorado on May 9, 2023.ISTOCK / GETTY IMAGES PLUSMeteorologist Kody Wilson tweeted a picture of these golfball-sized hailstones, while Twitter users @K_ann_hamilton and @u2videoqueen were among the many people who posted videos of the storm showing the hailstones crashing to the ground.
Miklós Szakáll, a research associate of aerosol and cloud physics at the Johannes Gutenberg-Universität Mainz in Germany, told Newsweek that "hailstorms are formed in the very large updraft regions of thunderstorm clouds. Inside those clouds exists a very complex air dynamics, i.e. there are regions where the updraft (vertical wind) is low, and in others the updraft is high."
In low updraft regions, small ice particles can be accumulated and grow relatively slowly by the processes of either diffusion or by something called "riming."
"After that, they get in a region with high updraft and carried to higher altitudes, i.e. lower temperatures, and grow further," Szakáll said. "The most efficient growth is riming, i.e. when an ice particle collides with supercooled liquid droplets which freeze on their surface. The other important growth process is the so-called diffusional growth, i.e. when water vapor condenses from the air onto the ice particle.
"In their lifetime from small ice particles to hailstone sizes, the hailstone experience different regions in the clouds, in which different temperatures and humidities present, and accordingly, different growth process is typical," he said.
"This lifetime is apparent from the ring structure which becomes visible when you cut a hailstone. If a hailstone is such big that the updraft cannot hold it in the cloud, it falls out. Since in large thunderstorm clouds, updraft speeds can be as high as 120 kilometers per hour (74.5 miles per hour), hailstone can grow to very large sizes."
The largest hailstone ever recorded fell in Vivian, South Dakota, on June 23, 2010, and measured 8 inches across. It weighed just under 2 pounds. Hail this size can cause a large amount of damage to homes and vehicles, and can even be deadly.
"The damage depends on the size of the hailstones," Andreas F. Prein, a project scientist at the National Center For Atmospheric Research in Boulder, Colorado, told Newsweek. "Smaller hail can already damage crops and plants while hail larger than 5 centimeters (2 inches) in diameter can cause severe damage to cars and some buildings. Hail the size of 10 cm (4 inches) or larger can severely damage buildings and can even be fatal."
This is because larger, heavier hailstones fall a lot faster, with the NOAA stating that hailstones less than 1 inch in diameter travel between 9 and 25 miles per hour, while those closer to 2 inches across fall at around 40 mph.
"Keeping your car in a garage is a good idea during days with severe thunderstorm risk," Prein said. "There is little people can do to protect their houses from large hail. If a large hailstorm passed over your neighborhood, I would recommend [checking] your roof for damage."
It's possible that we may see more hailstones like this in the future, and potentially larger hailstones, due to the effects of climate change.
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"It is a very good question whether hailstones will be larger due to climate change," Szakáll said. "The answer is very likely yes, although we might not experience that because the hailstones will be melted until they reach the ground. In a warmer climate updrafts will be stronger and the air will contain more humidity, which promotes the increase of typical hailstone sizes.
"Nevertheless, the temperature will be higher, and so the so-called melting layer, i.e. the altitude where the temperature is around 0 degrees celsius [32 degrees Fahrenheit], the melting point," he said. "If the melting layer is at a higher altitude, the falling hailstones will have more time to melt until they reach the ground.
"In this case, a hailstorm will arrive as heavy rain. There are studies which forecast in some regions more hail and larger stones but with hailstone less frequently, and regions where the hail size will decrease but the frequency of hailstorms increase."
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