Hail: Destruction and Beauty
Courtesy of The National
Oceanic and Atmospheric
Administration
In his poem, Fire and Ice, Robert Frost concludes that although fire's destructive capacity is greater, "ice is also great and would suffice". When it falls as hail, ice can cause huge amounts of damage in the course of a single storm, but hail is also fascinating: through its onion-like rings, one can read the history of a hailstone, a story that begins with a tiny speck inside an enormous cloud.
Hail is born inside a thunderhead or cumulonimbus cloud, the massive type of cloud that often produces thunderstorms. The tops of these clouds often reach elevations of 39,000 feet or more.
Hail forms in a thunderhead's main updraft, where the cloud is mostly made up of supercooled water (water which is liquid, but below the freezing point). When the supercooled water meets a foreign object such as a snow crystal, a frozen raindrop, a speck of dust or a particle of ocean salt it will cling to the object, creating the beginning of a hailstone. If the hailstone continues to float in the updrafts and downdrafts of the cloud regions where supercooled water is present, layer upon layer of ice will form, causing it to increase in size until cold downdrafts or gravity bring it down to the ground.
When a hailstone is cut in half, one can see the layers of ice like the rings of an onion, some opaque and others transparent depending on the temperatures at which the layer grew.
Official terms for the measurement of hailstones are quite picturesque, including peas, pennies or mothballs for smaller hailstones, and teacups, grapefruits and softballs for larger sized hail. The largest recorded hailstone to hit the United States fell on June 22, 2003 in Aurora, Nebraska. It had a diameter of 7 inches.
Although hail has its genesis from tiny specks of matter, it can be quite destructive. Hailstones can fall at speeds faster than 100 miles per hour, causing considerable damage to crops and property. In 1984, losses from a huge hailstorm in Munich, Germany totaled about a billion dollars. In 1990, a hailstorm in Denver, Colorado not only cost 625 million in property damages, it also injured forty-seven people who were battered by the softball-sized hailstones while trapped on a Ferris wheel during a power outage.
Because of the large amounts of damage caused by hail, meteorologists from around the world are engaged in research to find ways to suppress it or to reduce the size of the hailstones that fall. In areas where hail is common, they are assisted by volunteers from the public who use hail pads made from Styrofoam, which record the size, quantity and hardness of hailstones through the impressions left on the pads.
So far, the results of these studies have been inconclusive and hailstones continue to fall, pea-sized, or softball-sized, with all the destructive beauty of ice.
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