Weather Facts: Hail

AUSTIN, Texas - The last couple of weeks the storms have generated a mix bag of hail. FOX 7's Zack Shields takes a look at what causes the different sizes of hailstones.

The key ingredients for big hail events are very strong updrafts or rising motion to send the cloud tops higher in the atmosphere where the air is super cold.

As the raindrops float up and down in the clouds, they freeze as they go and melt when they drop. This process happens over and over so they can grow up into bigger chunks of ice.

The largest hail storms happen early in the spring because of the lingering winter chill aloft. The freezing layer is closer to the ground so hailstones don't melt as much as they travel toward the ground.

A hailstone can actually be sliced to reveal layers like a tree ring. Each layer represents one cycle through the storm.

The strength of the updraft in a storm is what determines the size. In a weak storm with updraft speeds around 30 to 40 mph the hail size will be small. When the rising motion increases to 50 mph the hail will reach severe levels and grow to quarter size. If the updrafts are going above the speed limit, look out for baseball to softball sized hail.