Hail is a type of precipitation, or water in the atmosphere. Hail is formed when drops of water freeze together in the cold upper regions of thunderstorm clouds. These chunks of ice are called hailstones. Most hailstones measure between 5 millimeters and 15 centimeters in diameter, and can be round or jagged.
Hailstones are not frozen raindrops. Frozen rain falls as water and freezes as it nears the ground. Hail actually falls as a solid.
Hailstones are formed by layers of water attaching and freezing in a large cloud. A frozen droplet begins to fall from a cloud during a storm, but is pushed back up into the cloud by a strong updraft of wind. When the hailstone is lifted, it hits liquid water droplets. Those droplets then freeze to the hailstone, adding another layer to it. The hailstone eventually falls to Earth when it becomes too heavy to remain in the cloud, or when the updraft stops or slows down.
Certain parts of the world receive more hail than others. The approach of the summer monsoon season in India brings severe thunderstorms, often with tornadoes and hail. A particularly deadly hail storm in Moradabad, India, in 1888 killed more than 250 people. China also experiences frequent hail storms, as do parts of the Midwestern United States. In fact, the Great Plains region of the United States and Canada is called "Hail Alley."
Hailstones can cause extreme damage to buildings, vehicles, and crops. Not surprisingly, people have tried to find ways to prevent hail. In the 18th century, Europeans began trying to prevent hail by firing cannons into clouds and ringing church bells.
In the 20th century, Russia and the United States tried cloud seeding. Cloud seeding is adding chemical particles into clouds from rockets or aircraft. Cloud seeding is thought to control rain and hail.
There is no clear evidence that any of these techniques are effective.
Look Out Below
In 1986, a hailstorm in Gopalganj, Bangladesh, killed 92 people. The hailstones were reported to weigh up to a kilogram (2 pounds).
Hail and Farewell
In 1360, a hailstorm outside Paris, France, killed hundreds of invading English soldiers. King Edward III soon gave up his conquest of France.
According to the National Severe Storms Laboratory, the largest hailstone recorded in the United States was found in Aurora, Nebraska, on June 22, 2004. It measured 17.8 centimeters (7 inches) in diameter and had a circumference of 47.6 centimeters (18.7 inches)about the size of a soccer ball.
vehicle able to travel and operate above the ground.
layers of gases surrounding a planet or other celestial body.
very large gun used for firing heavy projectiles.
visible mass of tiny water droplets or ice crystals in Earth's atmosphere.
process of adding chemical material to clouds in order to make it rain or otherwise control precipitation.
weather pattern of temperatures below 0 degrees Celsius (32 degrees Fahrenheit).
liquid precipitation that turns solid as it falls on a frozen surface.
grassland region of North America, between the Rocky Mountains and the Mississippi River.
precipitation that falls as ice.
the Great Plains region of the United States and Canada, which receives high amounts of hail.
individual chunk of ice that falls as precipitation.
to enter and attack.
having an uneven edge.
seasonal change in the direction of the prevailing winds of a region. Monsoon usually refers to the winds of the Indian Ocean and South Asia, which often bring heavy rains.
all forms in which water falls to Earth from the atmosphere.
to keep something from happening.
device that moves through the atmosphere by release of expanding gas.
person who serves in a military.
state of matter with a fixed shape and molecules that vibrate but do not move.
cloud that produces thunder and lightning, often accompanied by heavy rains.
a violently rotating column of air that forms at the bottom of a cloud and touches the ground.
device used for transportation.