HAIL
Hail is precipitation in the form of a lump of ice that starts as a raindrop falling from clouds. Updraft convection currents carry the raindrop back into freezing cloud regions, where layer after layer of supercooled water is added to the frozen drops. The added water also freezes and increases the sizes of the hailstones. Some hailstones have grown to the size of grapefruits. The largest hailstone recorded had a circumference of more than 47 cm.
Hailstones often consist of alternating layers of clear ice and cloudy ice. The clear ice forms as a hailstone passes through a layer of very moist air. The cloudy layer forms when water droplets freeze to the surface of the hailstone and trap air bubbles between them.
Hail’s Destructive Power
A hailstorm that lasts only a few minutes can cause tremendous damage. For example, hail has been responsible for some airplane crashes. It has torn holes in the roofs of houses and automobiles and in cabins of aircraft. Hail has killed people, livestock, and wildlife, and it has stripped plants of their leaves. In July 1984, a hailstorm in Germany caused $1 billion worth of damage to crops, trees, buildings, and vehicles. Trees were stripped of the bark. Crops were destroyed and nearly 400 people were injured.
The Cost of Hail
Hail destroys more than $200 million worth of wheat, corn, soybeans, and other crops in the United States each year. Hailstorms can have a devastating effect on individual farmers. Unlike drought, hail does not cause gradual damage. Instead, a family’s entire crop, which may represent work over an entire year, can be wiped out within minutes.
Questions
1. What is hail?
2. If you cut a hailstone in half, explain why you would see layering.
3. What causes the clear layer? Cloudy layer?
4. List 3 effects of how hail can be damaging.