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Thunderstorms

36 posts & 20 voices | Started 11 months ago by molgrips | Latest reply from andytherocketeer

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molgrips - Member

Here on the continent they do a nice line in apocalyptic thunderstorms at this time of year. Sky's gone pretty much black, now the wind's picked up a lot and some fairly constant rumbling is approaching.

Question though - more often than not there's almost continuous lightening but hardly any thunder. Last night it was clearly overhead (or thereabouts) but only faint rumblings. Could the activity really be at very high altitude? I mean I know there are high altitude phenomena but I always thought that was just an extension of the low down stuff.

Posted 11 months ago #
iDave - Member

Yeah huge one over the lake (Geneva) here a few days ago - I love 'em

Posted 11 months ago #
richmtb - Member

Well I'm no expert but this is t'internet so semi informed opinion is as good as

Thunder is caused by the explosive expansion of the air around the lightning stroke as its superheated to around 30,000 degrees C. My guess is that fork lightning that strikes the ground is passing through and heating much denser air (bigger bang) than it would be at altitude.

Thunderclouds (Cumulonumbus) can reach the top of the troposphere (12km up I think) and lighting up there would definitely make less of a bang than in the thinner air.

On top of this you also have to factor in that a lightning stroke 10km up in the atmosphere is immediately 10km further from your ears than one the strikes the ground nearby

Posted 11 months ago #
TheBrick - Member

maybe under some conditions the thunder is a very low frequency, inaudible (unaudible?) to the human ear?

Posted 11 months ago #
mastiles_fanylion - Member

Sounds cool!

I want to be there.

Posted 11 months ago #
CountZero - Member

Lightning inside a Cu-nim stack is going to be visible over a great distance, but the thunder won't be audible much over ten-twelve miles.

Posted 11 months ago #
kaesae - Member

I love large powerful storms, that said they do deserve and demand respect, always best to be prepared and take what ever precautions you can.

Any photo's or footage even linkies and this would become an awsome thread

Posted 11 months ago #
molgrips - Member

Will try and video the next one, only have a compact camera tho.

Posted 11 months ago #
mastiles_fanylion - Member

Pfft - nothing you saw will compare to this though.

Chilean volcano with lightening...

Posted 11 months ago #
molgrips - Member

MF that is a painting by Dante, not a photograph.

Posted 11 months ago #
mastiles_fanylion - Member

LOL is it?

Just trying to find pictures of the storm in the volcano last night.

Back to Google...

Posted 11 months ago #
mastiles_fanylion - Member

This one then...

Posted 11 months ago #
molgrips - Member

That is a graphic from Star Trek Voyager.

(btw not really they are both amazing photos, I was being silly and commenting on how impressively fantastical they are.. plus I'm also showing my ignorance.. apparently Dante wrote the poem Inferno and lots of other people did the paintings depicting crazy fire and flames like the volcano photo above... which I kind of knew but had forgotten)

Posted 11 months ago #
Urchinboy - Member

http://www.guardian.co.uk/world/gallery/2011/jun/05/chile-volcano-eruption-in-pictures

Posted 11 months ago #
mastiles_fanylion - Member

You little monkey, Molgrips, you.

Posted 11 months ago #
mogrim - Member

Got caught in a huge one yesterday, 40km of motorway fun on the motorbike. Never been that wet before fully dressed. Fortunately this time the phone survived.

Posted 11 months ago #
mountaincarrot - Member

I think it's to do with the temperature gradient. Warm air low down will refract the sound (which is going downwards from the thunderclap)progressively "away from the normal" and eventually send it skywards again.
It's the opposite of the effect you get on a cold clear morning with cold air at ground level, when you walk outside and realize you can hear that road a mile away which is normally inaudible.

Posted 11 months ago #
derek_starship - Member

I once spent 7 hours under canvas at a camp site in Avignon while the most powerful and protracted thunderstorm EVER raged outside. I was really scared! The lightning set several local woods on fire. I thought the end was nigher than usual. Impressive in retrospect though .

Posted 11 months ago #
molgrips - Member

Mountaincarrot - refraction, didn't think of that - good call.

Posted 11 months ago #
scuttler - Member

I always look forward to big storms on trips to Europe in Summer. I lived in New South Wales some years back and we had some good uns over there. A couple of pics with a compact camera (yes the night sky really was purple). And all accompanied by an eerie silence other than the sounds of the bush.

Posted 11 months ago #
molgrips - Member

How'd you get those with a compact? Just luck?

Posted 11 months ago #
crazy-legs - Member

Camping above Les Gets one year we were sat on the grass having our evening meal, bottle of wine and watching a very impressive storm over Mont Blanc. Couldn't hear anything at that distance but gradually the air got colder, stars were blotted out, we could hear the rumbles of thunder getting louder and we retreated under canvas just before the storm hit.

I loved it, there's something about being in a tent when all hell breaks loose outside. Provided of course that the tent doesn't leak...

Those shots from the Chilean Volcano are incredible. There were some similarly impressive ones from Iceland last year.

Posted 11 months ago #
scuttler - Member

How'd you get those with a compact? Just luck?

A bit of luck, a multi-shot option (Canon Ixus), a ton of lightning and a load of deleted photos at the end. The lightning was so intense and frequent it didn't take long.

Posted 11 months ago #
kaesae - Member

HAHAHAHA! molgrips, very funny!

Posted 11 months ago #
kaesae - Member

The power of that lightning from the chilean volcano photo is staggering

Posted 11 months ago #
Flaperon - Member

They're sparking up nicely all over Ljubljana at the moment - stunning display nearly all the way back from Paphos last week as we swerved around the bigger ones.

Posted 11 months ago #
fisha - Member

Thunder is caused by the explosive expansion of the air around the lightning stroke as its superheated to around 30,000 degrees C. My guess is that fork lightning that strikes the ground is passing through and heating much denser air (bigger bang) than it would be at altitude.

I thought the clap of thunder actually came from when the lightning bolt burns the volume of air its passing through, and leaves a temporary vacuum or hole in the atmosphere, the surrounding air then collapses into the hole/vacuum making the sound when it hits off itself on all sides round the hole. Just like the sound you get when you clap your hands together. ( hence a clap of thunder )

Posted 11 months ago #
Legoman - Member

We went through some impressive ones on Saturday on the way back from Les Arcs.

It prompted a brief debate over who was more likey to get struck by lighting - me with my alloy framed Trance on top of the car, or my mate with his carbon road bike on his car?

Posted 11 months ago #
mountaincarrot - Member

Yep close up ther's no "thunder sound", just one almighty crack. I've twice had lightening hit down within a few tens of metres, and it really is one hell of a bang.
So that's might be also true there Fisha. More air = more bang.

I was free flyiNg (hang gliding) in Italy under a CB some years ago (foolhardy perhaps). Up at about 7000 feet when lightening started coming out of the bottom, we all got out of there pretty quickly, but interestingly this was also silent even though we were at high altitude alongside it, probably just 1 OR 2km away. Possibly aforementioned refraction again.

Posted 11 months ago #
andytherocketeer - Member

Yep close up ther's no "thunder sound", just one almighty crack.

That's my experience. Very clean sound more like a whip crack. All the bang and rumble still comes later.
First experience here was when I was moving the furniture in. Stopped at traffic lights... "oh that lightning hit on the other side of the road". Then moving stuff from car in to house... "oh that lightning just went right over my head and hit next door".
Now I go out on the balcony and watch it strike the TV antenna mast next door... the mobile mast opposite... the crane on the next block...
But the lightning conductor on my bathroom skylight which runs across the bedroom and down the bedroom wall scares me. Dunno why.

Posted 11 months ago #
molgrips - Member

Very clean sound more like a whip crack

Closest I've been was probably 100m or so and it sounded like a bloody bomb going off, everyone ducked. Enormous KABOOOOM!

But the lightning conductor on my bathroom skylight which runs across the bedroom and down the bedroom wall scares me

Those things aren't there to conduct a strike to earth. They are there to diffuse charge so you don't actually get a strike in the first place. The term 'lightening conductor' is a bit of a misnomer.

Posted 11 months ago #
glenh - Member

p.s the closest I've been was bout 1m, and that also sounded (and looked) like a bomb (or at least what I imagine one would be like).

Posted 11 months ago #
portlyone - Member

Decent one over Manchester as we speak.

Posted 11 months ago #
Oggles - Member

We've got a few charlie bangers up in t'sky right now. Absolutely nothing compared to what we used to get in Texas though. The skies would turn a greenish hue and all hell would break loose.

Posted 11 months ago #
molgrips - Member

Oggles.. these continental ones are impressive but I'd love to see a US one once in my life. From the safety of a bunker or armoured car...

Posted 11 months ago #