The persecution
From mid -May until the end of June, Icechip storm hunters traveled through the front range of rock mountains and central plains, sometimes riding armored vehicles against the falling ice. They threw drones, launched meteorological balloons and established Doppler mobile radars, all the techniques perfected by hunter tornadoes.
As a group positioned Doppler’s mobile radars to intercept the storm at a short distance, other researchers were responsible for releasing nearby weather balloons or establishing sensors to measure the size and speed of a hail strike.
During some storms, the researchers published hundreds of pingpong ball -called devices called Hailsondes on the path of storms to track the life cycle of a hailstone, when it is melting and freezing, and how the dynamics of the wind that lifts and eliminates these pieces of ice affects its growth.
Convective electric storms, with large internal ascending currents, generate hail when circulating a mixture of water and ice crystals in the freezing layers of the upper atmosphere. The hail is typically formed at altitudes from 20,000 to 50,000 feet, where temperatures are among less 22 degrees and 14 degrees Fahrenheit. Those same routes of elevators sweep hail in the hail generating parts of each storm.
“If we can track that sensor over time, we are going to, at least for a couple of storms, understand the exact path, the exact trajectory that takes a hailstone,” said Victor Gensini, professor of meteorology at the University of the North of Illinois and principal researcher of Icechip.
In an atmosphere heated by climate change, “we get much more instability,” said Gensini, that researchers believe that they create stronger ascending currents.
Those stronger ascendants can support larger hail for longer, which allows ice balls or disks to win, before gravity sends them to the races to the ground.
“It’s something like you take a hair dryer and you put it at its end, it is quite easy to balance a pingpong ball, right, in that air stream,” Gensini explained. “But what would you need to balance softball? Would you need a much stronger ascending current.”
Storm modeling suggests that stronger ascending currents will increase the frequency of large hail in the future, even as the probability of hail in general decreases. The researchers suspect that little hail will decrease because its lowest mass means that it will take longer. By the time it is close to the surface, it has often melted to the water.
“There is this type of dichotomy, on the right, where you get a less small hail but a larger hail in these warmer atmospheres that have very strong ascending currents,” said Gensini.
During their field campaign, the researchers accumulated a collection of more than 10,000 hail in dry ice chests to try to determine if their computer models are obtaining the right hail growth dynamics.
“The hail record is a bit messy,” Gensini said about previous data, adding that observers have registered more than 2, 3 and 4 inches, but it is not clear if that is because more people pursue and find great hail or because the atmosphere is producing more.
Gensini said that new measurements will help researchers compare what is happening in the air with what they are finding on the field, which should improve hail forecasts and mitigate economic losses.
In many of the areas where ICECHIP is working, there is a lot of agriculture, according to Karen Kosiba, an atmospheric scientist of the flexible radar team and Mesonets of the University of Illinois who is also working with Icechip.
“It affects your crops, your machinery, putting things in refuge,” he said. “There are many economic ties with the weather.”
