All at one time we had clouds, sun, rain, snow and … HAIL?


I suspect that wasn’t hail but probably something called graupel. It is closely related to hail but forms differently.


Hail forms as rain falls from a thunderstorm, gets pushed back up high into the cloud by an updraft and freezing temperatures, freezes, then falls in a downdraft and gets wet from rain it collides with, gets caught up in another updraft and refreezes again. This can repeat many times, and each time the pellet freezes it grows bigger and bigger until the updraft can’t keep the stone suspended and it falls to the ground. That’s why very strong storms generate baseball- and grapefruit-sized hail at times. If you were to slice a hailstone in half you would see different layers, one for each trip back up into the cloud it made.


Graupel is formed when snowflakes form in a cloud and falling to the ground they come into contact with what is called supercooled water droplets. Those liquid drops are at a temperature colder than freezing but they don’t freeze. As soon as they come in contact with the snowflake, they freeze to it and form a pellet that is small, a bit “fuzzier” around the edges than hail and much softer. Most have never even heard of graupel and mistake it for hail.


The temperature profile of the atmosphere above us Wednesday in Southcentral Alaska wasn’t unstable enough to create hail, but was primed for graupel formation, which is why I think this is what took place.


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