Sherri Satterfield, age 12, of South Boston, Va., for her question:
HOW ARE HAILSTONES MADE?
Did you know that hailstorms are always closely connected with thunderstorms? But the regions of most frequent hailstorms are not the same as the regions of most frequent thunderstorms. In the United States, hailstorms occur most often near Cheyenne, Wyo., and Denver, Colo. Thunderstorms are most frequent near Tampa, Fla., and in northern New Mexico.
Hail is made up of roundish, hard balls of ice that fall from the clouds during some thunderstorms. Hailstones range from the size from tiny peas to the size of baseballs.
Hail is most likely to fall during the spring, but thunderstorms are most common in the summer. Hailstorms are almost unknown in the tropics, in the polar regions, in Florida and over the oceans. They occur almost exclusively between the lattitudes of 30 and 60 degrees. Hailstones most often have onionlike structures. They are made up of a number of layers of ice. Hailstones form much as sleet does. Small ice crystals or snowflakes contact supercooled water drops. A supercooled drop of water is one where it remains in liquid form even though the temperatures are below freezing. when the ice particles strike the supercooled water drops, the water flows over the ice. A part of it freezes instantly. Some unfrozen water stays attached to the growing hailstone until it freezes, and some of it escapes. This process continues until the hailstone falls out of the region of supercooled water. It may then be caught in an updraft and carried back into the supercooled water region, and again grow larger.
The process of a hailstone moving in and out of a region where supercooled water is located continues to produce additional layers of ice. This process continues until the updrafts can no longer support the hailstone. Finally it will fall to the ground.
Hailstones are not always carried up and down several times in and out of the supercooled water. Local variations in a cloud can cause irregular icing and the onionlike structure of a hailstone.
Scientists continue to hope to find a way to break up hailstorms by cloud seeding or some similar process. They want to lessen the damage hailstones bring to crops.
The largest hailstone on record in the United States measured 17 and a half inches around and weighed a pound and two thirds. It fell during a hailstorm that hit Coffeyville, Kansas, in 1970. Severe hailstorms, as you can imagine, are often extremely dangerous to people, animals and crops.