So, How Does Hail Form?

(credit: Meteorologist Jordan Rabinowitz)

As atmospheric science continues to evolve with time, there is no question that higher-resolution satellite imagery continues to change the way in which we study and evaluate severe weather events.

DISCUSSION: Throughout the Spring and Summer-time months, many people around the world who live across many inland areas are often increasingly more concerned about the relatively consistent threat which is imposed by strong to severe thunderstorm activity. As always, when it comes to strong to severe thunderstorm threats, there are many corresponding sub-threats that come along with the storms themselves. First and foremost, you generally will tend to have stronger winds courtesy of powerful downdrafts within more intense storms and then you will also find particularly heavier rainfall as well.  However, in addition to both of those severe storm components, you can also sometimes run across hail (and some destructive hail) depending on the specific situation.

Although many people around the world have experienced a hail event of some kind at some point during their lifetime, many people are uncertain or misled for how and why hail stones form in severe storms in the first place. There is a somewhat common misconception that chunks of ice “simply cannot ever occur during the Summer since the ice would melt before reaching the surface of the Earth.” However, this is a sincere error in judgement, since that cannot be farther from the truth.  In fact, hail forms within severe thunderstorms via very strong updrafts within a given thunderstorm suspending ice molecules within the higher parts of the thunderstorm.  During this process, a decent percentage of said ice molecules will collide and begin to “stick” to one another which increases the overall size of these individual ice molecules into smaller “pea-sized” ice chunks.  Depending on the strength of the main updraft within a given thunderstorm, the relatively small ice chunks may simply fall out of the cloud, but if the updraft remains strong enough, they will continue to remain suspended within the thunderstorm.

As they remain suspended, the smaller ice chunks will continue to undergo the process of aggregation and accretion which collectively act to further increase the average size of the smaller “ice chunks” into what atmospheric scientists more commonly refer to as hail stones.  Hail stones can be as small as “pea-sized” ice chunks as noted above or as large as softball and/or grapefruit-sized hail stones.  Thus, the destructive potential for larger hail stones is tremendous to say the very least. Hence, the next time you or someone you know is projected to be in the path of a nasty thunderstorm with a history of producing large hail, be sure to make the person aware of the incoming and potentially life-threatening situation so they can take proper shelter.

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© 2018 Meteorologist Jordan Rabinowitz