海角大神

Frozen clues: What hailstones say about a warming world

Researchers are chasing storms across multiple states to collect and study hailstones to better understand storm behavior. Their findings could reveal how climate change may impact future hail damage and storm intensity.

First Look

Dozens of researchers are chasing, driving, and running into storms to collect fresh hail, getting their car bodies and their own bodies dented in the name of science. They hope these hailstones will reveal secrets about storms, damage, and maybe the air itself.

But what do you do with nearly 4,000 melting iceballs?

A lot.

Researchers in the first-of-its-kind Project ICECHIP,聽In-situ Collaborative Experiment for the Collection of Hail In the Plains, to study hail are measuring the hailstones, weighing them, slicing them, crushing them, chilling them, driving them across several states, seeing what鈥檚 inside of them, and in some cases 鈥� which frankly is more about fun and curiosity 鈥� eating them.

The whole idea is to be 鈥渓earning information about what the hailstone was doing when it was in the storm,鈥� said Northern Illinois University meteorology professor Victor Gensini, one of the team鈥檚 lead scientists.

Calipers and crushers

It鈥檚 pushing midnight on June 20 in a Texas Walmart parking lot, and at least 10 vans full of students and full-time scientists are gathering after several hours of rigorous storm chasing. Hailstones are in coolers in most of these vehicles, and now it鈥檚 time to put them to the test.

Researchers use calipers to measure the width, in millimeters, of the hailstones, which are then weighed. So far after more than 13 storms, the biggest they found is 139 millimeters (5.5 inches), the size of a DVD. But on this night they are smaller than golf balls.

Once the measurements are recorded in a laptop, the fun starts in the back of a van with a shark-festooned beach blanket protecting the floor.

The hail is put on a vertical device鈥檚 white holder. Jake Sorber, a meteorologist at the Insurance Institute for Business and Home Safety, squeezes a hand grip about a foot above it, and another white block comes crashing down, crushing the ice to smithereens. In the front of the van, Ian Giammanco, another IBHS meteorologist, records how much force it took to cause the destruction.

鈥淭hat tells us about its strength,鈥� Mr. Giammanco said.

Different teams do this over and over, with the debris littering vans. It鈥檚 all about trying to get good statistics on how strong the typical hailstone is. On this night, Mr. Giammanco and colleagues are finding the day鈥檚 hail is unusually soft. It鈥檚 surprising, but there鈥檚 a good theory on what鈥檚 happening.

鈥淚n hailstones we have layers. So we start off with an embryo, and then you鈥檝e got different growth layers,鈥� said Central Michigan University scientist John Allen. 鈥淭hat white growth is what鈥檚 called dry growth. So basically it鈥檚 so cold that it鈥檚 like super cold liquid water freezing on surface. ... All the gas gets trapped inside. So there鈥檚 lots of air bubbles. They tend to make a weak stone.鈥�

But don鈥檛 get used to it. Less cold air from climate change could conceivably mean harder hail in the future, but more research is needed to see if that鈥檚 the case, Mr. Giammanco said.

鈥淒amage from a hailstone is not just dependent on how fast and the exact amount of energy it has. It鈥檚 how strong are these hailstones,鈥� Mr. Giammanco said. 鈥淪o a really soft one is not actually going to damage your roof very much, especially an asphalt shingle roof. But a really strong one may crack and tear that asphalt shingle pretty easily.鈥�

How to collect a pristine hailstone

Mostly researchers grab hail to test after it falls, wearing gloves so as not to warm or taint the ice balls too much.

But to collect pristine hail and get it cold as soon as possible, there鈥檚 SUMHO, a Super Mobile Hail Observatory. It鈥檚 a chest-high metal funnel that catches hail and slides it directly down into a cooler. No contamination, no warming.

Most of these pristine hailstones go directly to a cold lab in Colorado, where they are sliced with a hot wire band saw. The different layers 鈥� like a tree鈥檚 rings 鈥� will help scientists learn about the short but rapid growth of the ice in the storm, Mr. Gensini said.

Scientists will also figure out what鈥檚 in the hail besides water. Past research has found fungi, bacteria, peat moss and microplastics, all of which helps researchers know a bit more about what鈥檚 in the air that we don鈥檛 see.

After weeks of collecting these ice balls, Central Michigan student Sam Baron sampled the fruit of his labors.

鈥淚t tastes like an ice cube,鈥� Mr. Baron said. 鈥淚t鈥檚 like the good ice that they serve at restaurants.鈥�

This story was reported by The Associated Press.