Morning All, When you have torrential rain you sometimes get the odd random clap of thunder (and Accompanied lightning) At what point does a collection of lightning flashes and thunder claps get classified as a storm? Sometimes their seems to be lots of lightning strikes in areas but don't get given a storm status? Their must be a threshold point that difines a thundery downpour as apposed to being a Thunderstorm. What I am trying to ask (Not explaining what I mean very well here) Basically what criteria turns a thundery shower into a trackable, named STORM?? Very interested to know answers/opinions on this one folks. Thanks in anticipation of some good answers on this. Virtual Stormchaser

Hi, great question. One many of us have asked ourselves im sure.

Here are some definintions I have come accross.

THUNDERSTORM

It is relatively small and quick, about 15 miles wide and lasts 20 to 30 minutes. At minimum, hail must be ¾-inch in diameter, winds must be 58 mph or it must contain a tornado, and it always contains lightning.

THUNDERSTORM

Any short-lived, violent atmospheric disturbance characterised by thunder, lightning, gusty surface winds, hail, precipitation,etc constitutes a thunderstorm. It is an event of relatively short duration. Water drops from a thunderstorm are small, and they evaporate before reaching the ground as precipitation.

My thoughts are that if lightning occurs on a regular basis, rather than a one off, it's a storm.

Clive.

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Thanks Clive, the second definition seems to say that a Thunderstorm does not have rain? "Water drops from a thunderstorm are small, and they evaporate before reaching the ground as precipitation" That cannot be correct surely? Also a scale of storm ferocity would be a good idea? especially for newbies. For Example you could have a heavy shower, no hail 1-2 lighning events could be classed as a +2 and then at the other end maybe Heavy, Large rain, big hail, more than 100 lightning events Etc, + Etc, could be a +100 perhaps with a letter or two to indicate the ferocity of Lightning IE cloud to ground beeing the dangerous factor and or other relevant info? what do you reckon??? Does it exist already? If not does anyone fancy a collaboration? For someone just getting into Sferics/severe weather, it might be a great help. Cheers; Virtual Stormchaser

may be of interest VSC - - TORRO: Research: Hint For Observers

regards

Brett

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