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Britta's Weather Lab: How does hail happen?

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HOUSTON – The key to all weather is that warm air rises. Warm air is less dense and rises high into the atmosphere. It runs into cool air where condensation occurs and clouds start to build.  

If this continues to happen, eventually a rain cloud will form. As more air rises, a shower continues to grow higher into the atmosphere reaching the same elevation where air planes soar! 

When storms grow to this level, thunderstorms become very strong. The warm air that continues to rises into the storm is called an updraft.

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Water droplets catch a ride on these updrafts and are pushed to the top of the thunderstorm where it is very cold freezing them into tiny bits of ice.

The chunks of ice continue to move up and down inside the thunderstorm adding a layer of ice with every trip.  

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Eventually, the ice chunks grow so big and become so heavy that the updrafts can't push them upward. The chunks fall due to gravity hitting the ground below as hail.

If a hail stone is cut in half, layers of ice are revealed very similar to a tree ring showing the many trips the hail stone took up and down inside the thunderstorm before falling to the ground.


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