Lightning Questions

[Mesoscale]

Hey everyone! Ive got a bit tired of winter posts for now so i thought id start this as it confuses me so much (sorry if this has been talked about but i searched, honestly!)

Heres my experiences that made me think about these questions!

For a while I have been wondering what determines how much lightning a storm will produce?

I have some examples for you:

On monday a storm dubbed 'fall fury' which i think is very tacky, pounded the US with there lowest ever non tropical storm pressure of 955, that brought snow and strong winds to North/South Dakota, Minnesota and into the great lakes, it produced a line of severe storms from Tennessee to Canada with striaght line winds of 60-70mph but over all there wern't many lighting strikes at the time i was on WLWT.com watching live coverage as the line moved through the Cincinnati, Ohio area I was watching for a solid 45 minutes and out of that whole time only 2 lightning strikes were detected these storms were very powerful and produced an EF2 north on Cincinnati? why didn't they have many lightning strikes?

Another example was when I was in florida august 2009, most days you would see a bit of lightning here and there nearly everyday it would almost completly cloud over by lunch time and in the afternoon you get popcorn storms with a bit of lightning nothing too dramatic but on one day I went shopping at the florida mall (great place by the way) it was 35C with humidity walking across this massive carpark no more then 1/4 of a mile was horrible! after id done my shopping I came out and noticed some absoloutley HUGE cumulonimbus, Driving back to international drive I could see literally a sheer wall up the side of one of them at the time it was still building but it was heading in our direction, we went to wall mart to get some ponchos as we where heading to busch gardens the next day (wet rides) we came out just as the storm hit downtown orlando, the storm just exploded there was constant thunder/lightning, it was absolutley amazing 2500+ lightning strikes were recorded in the two hours it was over mid florida, i got up at about 3 am to get a drink that night and could still see the lightning from it even though it started at about 5pm what determined that that storm would grow huge and create alot of lightning and the other storms in the midwest to grow huge but not produce alot of lightning?

another lightning question everytime ive seen a storm in the UK the thunder is always loud, really agressive and literally vibrates the house,

but in florida the thunder does not seem as poweful as lightning here the same goes with mexico i went this year in july and we had a whole night filled with thunderstorms one after the other the thunder was quite loud but just seemed muffled like somebody had put a towel over my ears, mexico was a good time for me after the night of storms it rained for two days straight as a tropical wave was heading over us it was also good because we had some great storms I was nearlly killed as we went to a water/ecological park on one of the days and about 3 thunderstorms came rolling through one after the other, they have no safety there what so ever as we where aloud to enter the pools as the lightning was striking within a mile away from the location at times. We decided to go under some shelter as the final storm was passing and it started to pelt down I went out in it as at that time it was only really heavy rain it started to hail and it hurt (only pea sized hail) and lightning started to flicker across the sky so i decided to go back to the shelter but my dad being my dad hes like 'i need the toilet' so we start walking to the toilet just down the beach the lightning is getting pretty close now and im actually worried at that point, the thunder is literally coming straight after the lightning i suggest that we wait in the cover of the toilets untill it passes, my dads like 'no we will be fine the trees are taller then us it will hit them first' against my better judgement we moved off down the beach as we get halfway down FLASH and the sound of a arcing then BOOOOOOOOOOOOOOOOOOM all together! I nearly through myself on the floor as the beach about 5 metres in front of me gets showered with smoldering bits of palm tree, it really scared me we probably all had positive leaders coming from the top of our heads none of us felt our hair start to stand on end probably because we were soaked from being in the water that day and it pelting down. the storms that day were literally all forked lightning what makes a storm only produce forked lightning?

Sorry for the essay but I love to tell my experiences! and sorry for all the questions!

Edited October 29, 2010 by Mesoscale

[Terminal Moraine]

The number of lightning strikes within a storm is dependant upon the charge differential within the vertical layers of the storm. The electrical charge within a storm is built up by turbulence. Updraughts carry liquid water droplets high above the freezing level and downdraughts carry ice and hail. Where the two mix, the water droplets freeze and release heat,causing the hail and ice to turn into a sort of soft hail/graupel mixture.

As this graupel collides with other ice particles and water droplets negatively charged electrons are sheared off and attach themselves to the falling particles, this has the end result of the storm cloud developing a negatively charged base and a positively charged top ( although there are several layers of negative and positive charge within the storm cloud )

Simply speaking, the greater the turbulence and the deeper the cloud the greater the differential in charge between the top and the base and the more frequent and powerful the lightning. Large slow moving storms with great turbulence and very high cloud tops will therefore have more lightning than storms resulting from relatively small clouds where the charge differential is smaller.

At the same time as all this is happening within the cloud a positive charge builds up at ground level and this follows the track of the storm. The differential in charge between the ground and the cloud is however much less than the differential within the cloud which is why some storms seem to produce much more intra- cloud lightning than cloud to ground strikes.

The loudness of thunder is dependant on a number of factors but, generally speaking, thunder resulting from lightning within the cloud will sound more muffled than that resulting from cloud to ground strikes. As a rule of thumb the closer you are to a ground strike the louder the thunder will sound.