Wednesday, December 24, 2008

What causes Hail?

One of the unusual weather conditions we can experience is a hailstorm. It is quite a thing to see and hear hailstones coming down, sometimes with such force that great damage is done. Animals, and even men, have been killed by hail!

A hailstorm usually occurs during the warm weather and is accompanied in many cases by thunder, lightning and rain. Hail is formed when raindrops freeze while passing through a belt of cold air on their way to earth.

Hailstorm lashes Lismore

Single raindrops form very small hailstones. It is interesting to note when a raindrop falls as a hailstone, it may meet with a strong rising current of air. so, it is carried up again to the level where the raindrops are falling. New drops begin to cling to the hailstone. And as it falls once more through the cold belt, these new drops spread into a layer around it and freeze, and now we have larger hailstones.

Hailstones, in size of a tennis-ball

This rising and falling of the hailstone may be repeated time after time until it has added so many layers that its weight is heavy enough to overcome the force of the rising current of air. Now it falls to the ground.

A field littered with large hailstones right after a summer hailstorm.

Hailstones measuring three or four inches in diameter and weighing as much as a pound are sometimes built up. Snow too freezes around hailstones when they are carried into regions where it is forming. Thus, the hailstones are frequently made up of layers of ice and snow.

Largest Hailstone ever measured (17.8 cm in diameter and a 47.6 cm in circumference)

Hailstorm in Bogota, Colombia

On 20 April 1888 in Moradabad, India, 246 people (along with more than 1,600 sheep and goats) were killed by hailstones, some as big as cricket balls. Hailstones can be a dangerous hazard, especially if they get very large. They can do tremendous damage to property and have even been know to kill cattle!

A larger hailstone has broken the win shield

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