Hailstone structure

[Jimmy Deguara]

Most of my chasing within Australia is aligned with trying to predict and chase hail conditions. My last storm chase was on Monday not too distanct from the Mudgee hailstorm in January.

What is interesting from my perspective and the main purpose of this thread is for others to show structure photographs of hailstones they have intercepted. Here is the picture from Monday 20th February 2006 (diameter 5cm)

The concentric rings of such hail sizes are not something I am used to seeing given this sized hail.

Regards,

Jimmy Deguara

 

[cdcollura]

Good day,

The rings you see in hail are like rings of a tree trunk that has been cut. Just like the tree, where the rings are caused by variations in the seasons (therefore years), the hailstone is caused by variations in temperature and freezing at different altitudes (clear ice being higher up).

Each ring represents a trip up and down the thunderstorm updraft (which can be displacements of 20,000 or even 30,000 feet)!

The updraft (or hailstone up / down) speed and "ice accretion" rate determines the thickness of each of the "rings" in the hailstone itself.

Chris C - KG4PJN

 

[Glen Romine]

The idea of hail recycling (the stone falling, getting caught up in the updraft, falling again, etc...), as discussed by Chris above, has been found to be rather rare. Instead, the normal trajectory is simply an up and down. While the ringed appearance does indeed show the hailstone was growing in a differing environment over time - that doesn't necessarily mean it was moving up and down in the updraft to produce it. Instead - it indicates changes in the liquid water content relative to the environment temperature, namely how able was the hailstone to freeze all of the water making contact with it. When the hailstone is intercepting water faster than it can freeze it (called wet growth), the hailstone ice appears clear, whereas when the hailstone is more effective at freezing all of the liquid water droplets it intercepts, it will have more air trapped in the hailstone making it appear more white (called dry growth).

Glen

 

[John Farley]

Here's a nice example, from the St. Louis NWS, of concentric rings in hail from the February 16 hailstorm in the St. Louis area:

http://www.crh.noaa.gov/crnews/display_sto...d=1570&source=0

Note that this hail is similar in size to the stones in Jimmy's photo. I did not witness this storm, because I was already in Colorado to do a little skiing before the chaser convention. OTOH, my car came within a mile or so of encountering it while parked at the St. Louis airport, as the hail passed just west and north of the airport. I was relieved to get back and see no damage to the car. Still some nice piles of hail along I-270 when I got home from the chaser convention, though of course not much to melt them once the cold front came through right behind the supercell that produced the hail.

 

[Pat Lawrence]

Originally posted by Glen Romine
The idea of hail recycling (the stone falling, getting caught up in the updraft, falling again, etc...), as discussed by Chris above, has been found to be rather rare. Instead, the normal trajectory is simply an up and down. While the ringed appearance does indeed show the hailstone was growing in a differing environment over time - that doesn't necessarily mean it was moving up and down in the updraft to produce it. Instead - it indicates changes in the liquid water content relative to the environment temperature, namely how able was the hailstone to freeze all of the water making contact with it. When the hailstone is intercepting water faster than it can freeze it (called wet growth), the hailstone ice appears clear, whereas when the hailstone is more effective at freezing all of the liquid water droplets it intercepts, it will have more air trapped in the hailstone making it appear more white (called dry growth).

Glen

This is interesting information, Glen. I had never read, or heard about, anything other than the old up and down thing.

Thanks for the new information!

Pat

 

[Jimmy Deguara]

Hi John,

Thanks for your input and the input of others on here. I have seen, measured and experienced larger hail even in Australia but these caught my attention compared to anything else I had witnessed in the past.

Sorry, I don't see much of a similarity here unless you are referring to inner structure of the one on the left. The hailstones I collected were as found and very near perfect which I found rather unusual - usually indicative of hailstones 2 to 3cm in diameter rather than 5 or greater.

Also, it seems the storm from a visual perspective and what seems to be the case on radar although containing explosive updraughts most likely was a sever multicell!

Regards,

Jimmy Deguara

 

[John Farley]

Originally posted by Jimmy Deguara
Sorry, I don't see much of a similarity here unless you are referring to inner structure of the one on the left. The hailstones I collected were as found and very near perfect which I found rather unusual - usually indicative of hailstones 2 to 3cm in diameter rather than 5 or greater.

I was referring to the concentric rings and the size of the stones, not the shape. Yes, the ones you observed were much rounder than the St. Louis ones. I have seen very round stones as large as 4" in diameter (west-central Oklahoma, May 29, 2004), but I agree that usually the larger stones are more irregularly shaped.

Originally posted by Jimmy Deguara
Also, it seems the storm from a visual perspective and what seems to be the case on radar although containing explosive updraughts most likely was a sever multicell!

Not sure here whether you are referring to the storm you observed or the St. Louis storm. The St. Louis storm was tornado-warned and showed strong rotation on radar, and produced large hail on a fairly long swath through St. Louis County, probably far north St. Louis city, and into Madison County, IL, so I think supercell would be an appropriate description of it, although it certainly was part of a larger complex that included numerous other storms.

 

[Jimmy Deguara]

Hi John,

Sorry - yes the storm I observed and its radar echos and updraft behaviour were indicative of multicell behaviour. All hailstones 5cm and greater I have observed thus far were from supercells - this is a non-supercellular case.

Rounded 4" hail with concentric rings? Have you or anyone got photographs as they would eb interesting to see? I am trying to recall whether the photographs from Fort Worth had such?

What conditions create such perfect large hailstones? I would like to see others post other examples of perfect very large hailstone photographs re circular or elliptical shape in nature with concentric rings. A different topic for a change.

Regards,

Jimmy Deguara

 

[Andrew Khan]

Hello,

Essentially, how high up can a hail-stone ascend to the atmosphere? A couple of months ago, I was told they could reach heights of 50,000 FT, but I am not sure if this is a fact or fiction.

 

[John Farley]

Rounded 4" hail with concentric rings? Have you or anyone got photographs as they would eb interesting to see? I am trying to recall whether the photographs from Fort Worth had such?

A clarification - there were definitely round hailstones 4 inches and larger, but I can't verify whether they had concentric rings. I was trying to catch up with the storm and did not stop where I saw those stones, but there were quite a number of them. (I did photograph some smaller ones later, as linked below.) Storm Data includes reports of stones as large as 4.75 inches near Custer City with that storm, which was a long-track HP supercell that moved nearly all the way across Oklahoma and produced a number of tornadoes, mostly rain-wrapped (but several anticyclonic ones that were not rainwrapped).

A picture of a hailstone from that storm around 2 to 2.5" in diameter can be seen here:

http://www.siue.edu/~jfarley/chase%20529047.jpg

The bigger ones I saw were pretty much the same shape as this one. Again, though, I don't know whether they had concentric rings.

One correction - that date of the storm was May 28, 2004, not May 29 as I erroneously said in my earlier post.

 

[Jimmy Deguara]

Actually John,

Unless you had some other storm I had not heard about ie 26th May 2004, then 29th May was correct:

This is the one we chased although we did not see the hailstones:

http://www.australiasevereweather.com/vide...4/20040529.html

Regards,

Jimmy Deguara

 

[John Farley]

Yes, I was right in the first place - May 29. Sorry for the confusion. And yes, we were on the same storm. You did better in the tornado department, though.

 

[Mike Johnston]

Pat wrote:

"This is interesting information, Glen. I had never read, or heard about, anything other than the old up and down thing.

Thanks for the new information! "

I heartily second that! Thanks so much Glen, for a great informative post. As I think someone mentioned on another thread, we really, really welcome and appreciate those of you in the forefront who graciously inform and educate us on meteorological science. I have hardly ever failed to learn and pick up something new and informative from guys like you and Jeff Snyder...freely given and thankfully received; it is truly appreciated.