It just stopped hailing around here… which got me thinking.
Why does it only seem to hail for relatively short periods of time? It can rain or snow for days on end, but it never hails for that long (thank god). What’s up?
Once a storm encounters a large cold air mass aloft, the precip can freeze and refreeze until it’s hail sized.
The cold airmass aloft will eventually warm up, ending the hail event.
It takes a great deal of energy to produce hail. What happens is that raindrops are driven upwards in the cloud by updrafts to cold regions where they freeze and collect additional ice. Eventually the stones get big and heavy enough that this updraft cannot keep them aloft anymore, they then fall to the earth, if they are large enough, they won’t melt entirely before impact.
Neither snow nor rain require such a powerful updraft to be maintained, they can just collect themselves and fall naturally. This is why hail only occurs during heavy storms, only they can produce the updraft necessary, and only for limited periods of time.
Here’s a bit more info from USA Today
Just as an aside, snow is precipitation formed in the frozen state, and remaining frozen as it falls. Sleet forms in a liquid state and freezes as it falls to the ground. Freezing rain forms as a liquid and freezes on contact with the frozen ground. Rain either forms as a liquid and stays that way, or forms frozen and melts on its way down.
Hail differs from sleet in that it is formed liquid, freezes in the cloud, often building considerable size due to the updraft keeping it aloft, then falling to the ground. Sleet falls initially as rain and freezes along the way by passing into cold air.