How is hail formed in thunderclouds?

[LeonStanley]

Hi Ladies and Gentlemen

Watching an episode of Mythbusters a couple of weeks ago, . . it just hit me .. maybe this is how ice is formed in clouds.

You have a supercooled bottle of waterbased liquid. You strike a blow to the bottle and watch the liquid turn instanly into ice.

Is not it possible that the sonic boom of lightning would cause the supercooled rain drops to turn to ice. ? ?
If so, this explain why hail is usually all of a uniform size.
If so, this might explain the colours you see in clouds when the lightning lights them up - either a pinkish or greenish hue - because some wavelength might be used up in the change of state (liquid to solid) of the rain drops.

 

[davenn]

Hi Ladies and Gentlemen

SNIP

Is not it possible that the sonic boom of lightning would cause the supercooled rain drops to turn to ice. ? ?

Maybe its one reason, but hail can still often form when there is an absence of lightning

If so, this explain why hail is usually all of a uniform size.

well if you have done lots of storm chasing like I have ... you will soon realize that hail ISNT uniform in size. Varies from less than pea size to an inch or 2 for an individual stone. The really, really large hailstones greater than 2 inch and up to ~ 7 - 8 inches tend to be a "welded" mass of the 1/2 - 1 inch stones

If so, this might explain the colours you see in clouds when the lightning lights them up - either a pinkish or greenish hue - because some wavelength might be used up in the change of state (liquid to solid) of the rain drops.

The common greenish colour in the storm clouds, often indicating a presence of hail, is there regardless of if there is a lightning flash or not.

Just some observations from many years of stormchasing/photography both in Australia and the USA.

cheers
Dave

 

[Drakkith]

You don't agree with the current view of how ice and hail is formed in a storm?
http://en.wikipedia.org/wiki/Hail

 

[Drakkith]

Davenn, during your time as a stormchaser, did you ever encounter anything that just defied explanations or was totally unexpected?

 

[davenn]

You don't agree with the current view of how ice and hail is formed in a storm?
http://en.wikipedia.org/wiki/Hail

you referring to me or the OP ?

I totally agree with the wiki info and it even shows one of those nice large mass of welded together smaller stones The second pic under the large font "Definition".

The larger stones are almost always like this or extremely irregular and pointy like the ones down the page with the ruler and $20 bill. The larger the updraught the larger the stones.
The other thing is ... the larger the stones often the less of them falling from the clouds!
They just do more damage when they do hit something :(

Dave

 

[davenn]

Davenn, during your time as a stormchaser, did you ever encounter anything that just defied explanations or was totally unexpected?

hmmmm, you have me pondering... ;)

can't think of anything specific off the top of my head... will get back to you on that.

Storms and their formation, do have a certain amount of predictability.
What I mean by that, is thay we can look at the metorological setup a day or so before and have a pretty good idea when and where we will see action. Then drive 100's of km's to get into the right area. Being able to read the met charts, ie. atmospheric soundings etc it means we can get into the right area to see the action start up. Then once it starts firing up using the weather radar to watch individual cells. Sometimes its (what we in the chasing game call) a "bust", things just fail to kick into action. Often for unknown reasons, other times we can see atmospheric effects that hampered the cell growth, eg a cap up at ~ 2000 metres. You will watch the cells start forming, the towers going up and then they just stop.
Temperatures almost always cool with altitude, but a "capped" environment can inhibit T-storm growth - an inversion (a warmer layer of air several 1000 metres overhead) can act like a brake on rising thermals of warm air, preventing storms from firing. But if there's enough upward motion, an approaching storm high up (or surface heating) this "cap" can be overcome. Once the updraft breaks through the inversion storms can mushroom in minutes.
Other times the cap is just too strong, and the rising thermals just can't break through.

OK there's my MET101 stormchasers lesson for the day hahaha

I still can't think of anything really out of the ordinary/weird.
Some storms I watch and photo and think ohh that was good... then there are the rarer others that have just left me standing there saying WOW WOW over and over with an amazing structure of the storm cell... those O.M.G moments :)

cheers
Dave

 

[Drakkith]

you referring to me or the OP ?

The op.

Sounds like a fun and rewarding job you have there. So many variables! So little time!

 

[LeonStanley]

Thanks Gentlemen for your input to this thread.

My original post was purely speculative. I read the wiki link thanks Drakkith. I agree with the general science there, but could not find anything to definitely negate the possibillity that the raindrops can be formed instantly into hail either.

And also Dave, it has been my experience that hail is usually all of a characteristic size - either all small, medium, or large. Sure there are some odd larger or smaller ones, but most are all similar in size - in a typical drop.
When I referred to the colours seen in thunderclouds, I meant at night in the dark when you see a cloud lit up by flashes. I have seen just about every colour tint concievealbe - pink, orange, purple, and yellow. Sometimes the cloud itself, but often the colour was seen in the fingered sheet lightning itself. I was told by a pilot that the colour is indicative of ice being in the cloud.