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Thunderless lightning...

I can think of five possible reasons for thunderless lightning....

1. The lightning is so far away that the sound of the thunder has diffracted away and is therefore inaudible.
2. Competing sounds muffling the sound of the thunder.
3. Intervening objects deflecting the sound of the thunder away.
4. Heavy winds travelling away from you towards the lightning and carrying the sound away with it.
5. Deaf observer.

Thunderless lightning is not exactly a rare occurence at least around these parts and the reason almost always seems to be (1)above.

I think it would be almost impossible to visually estimate the distance to the lightning - is it a dull flash nearby or does it appear dull because it's far away? Is it a bright flash because it is nearby or is it an extremely bright flash that only seems bright because it's far away?
 
To BJ:

I can think of five possible reasons for thunderless lightning....

1. The lightning is so far away that the sound of the thunder has diffracted away and is therefore inaudible.

*Nope, at time I could almost guarantee it was closer than 3400 feet.

2. Competing sounds muffling the sound of the thunder.

*The thunderstorm was the only major sounds to be heard, no trains, planes, or automobiles.

3. Intervening objects deflecting the sound of the thunder away.

*Wind is the only culpret I have been able blaim.

4. Heavy winds travelling away from you towards the lightning and carrying the sound away with it.

*Possibly.

5. Deaf observer.

*Nope, my hearing is first rate.

Thunderless lightning is not exactly a rare occurence at least around these parts and the reason almost always seems to be (1)above.

I think it would be almost impossible to visually estimate the distance to the lightning - is it a dull flash nearby or does it appear dull because it's far away? Is it a bright flash because it is nearby or is it an extremely bright flash that only seems bright because it's far away?

Have you ever been closer than 150 yards to a lighting strike, that DIDN'T result in a loud clap?

After the storm, days later I found out that lightening struck one of my neighbor's trees. My neighbor said he SAW the strike, and that it didn't make any sound...

I have as of yet been unable to decipher the nature of this phenomonia.
 
I experienced something very similar many years ago. I was only about 8 or 9 years old, and I was staying with my parents in a hotel where the adults had dinner later than children's tea. My parents were at dinner, and I was in the hotel bedroom alone, but too big to have been put to bed (it would be about 7.30).

The window of the room looked out into an inner courtyard of the hotel - not all that pleasant, more a service area than a flowerbed. I remember a very marked electrical storm, unusual occurrence for Scotland. The weird bit was that although the room was quiet and there was nothing much else going on, I heard no thunder. And it didn't seem to be far away, because there wasn't much of a view from that room in the first place. In fact, once or twice I was sure the lightning actually flashed inside the courtyard I was looking into. I didn't think anything was hit at all - it was all beautifully silent.

I was too young to think it was an especially inexplicable thing, and kind of assumed that if you were close enough then maybe you didn't hear the thunder.

Mind you, the lightning bolt which I think nixed my previous computer in May this year was very close indeed to where I was standing watching (didn't hit either, but I think there must have been a surge), and the flash was followed almost immediately by a loud thunderclap. So, I dunno.

Rolfe.
 
Well...

...EVERYTHING I have read has held the stance that ALL lightening makes thunder. However, sometimes wind, distane, ad temperature can create barrers to the thunder.

My findings and experience counter this stance and demand that either that ther are other factors stopping thunder, or 'some lightening' simply doesn't produce thunder.

Of the two I am leaning toward the latter.
 
KOA,

King of the Americas said:
My findings and experience counter this stance and demand that either that ther are other factors stopping thunder, or 'some lightening' simply doesn't produce thunder.

Of the two I am leaning toward the latter.
Click to expand...
Now all you need is a mechanism.
Good luck with that.

BJ
(And don't lean too far you might just...... :D )
 
I've seen a big storm without thunder as well.

I went searching found a lot of "it's more than 15 miles away" then I found this... :)

Lightning without thunder is called heat lightning or wildfire, and is usually intracloud or cloud-to-cloud discharges at altitude. It occurs on warm evenings in humid regions where the lapse rate is large, so that most of the thunder is directed upwards and does not reach the ground. It was the large lapse rate that produced all the clouds. If extensive, it is dramatic and beautiful, illuminating broad areas of cloud in flashes, sometimes behind dark obscuring cloud screens.
Click to expand...

http://www.du.edu/~jcalvert/weather/tstorm.htm

It has information on what this "lapse rate" is as well:

The Sun heats the surface of the earth strongly, drying it out and making a layer of hot, humid air there. Since the atmosphere is heated from below and cooled from above, the air rapidly cools with height, at an average rate of perhaps 6.5°C per km (called the lapse rate), and the atmospheric pressure decreases rapidly as well. On these hot days, however, the temperature often decreases even more rapidly, and the lapse rate is often superadiabatic, meaning that it cools more rapidly than a rising parcel of air cools by expansion. Should a hot parcel of air rise a little, it finds itself a bit cooler, but still hotter than the air around it, so it is buoyed up higher, and the same thing happens again. The hot, humid air at the surface is convecting, driven by the buoyant forces of cool air that keeps coming in at the sides to equalize the pressure, while more hot air arrives from the surface.
Click to expand...
 
So, is this the mechanism?....

The hotter surface air rises into the colder upper layers dragging the sound of the thunder with it just like the wind does (remembering, of course that sound is just compressions and rarefactions in the air)

Sounds good to me! :D

BillyJoe
 
I'd guess another way of looking at it is those rare rotating thunderstorms that are strong enough to generate large tornados might also generate much wider but much weaker suction-effects, probably over an area many kilometers across.

So just occasionally, you might get thunderstorms where you can be right under cloud-to-cloud lightning and not hear anything at all as the sound gets sucked straight back into the cloud.
 
I have...

...heard this phenomonia referred to as "heat lightening", but have read very little in the way of 'scientific studies' upon the subject.

My understanding of 'thunder' came from my physical science textbook, that said the sound associated with lightening was a result of the air clapping back together, because the lightening broke the sound barrer causing a sonic boom...

Up until just a couple of years ago, this is what I thought I was seeing and hearing...

As I understand Science's 'current' explaination is that the air is actually being 'popped' when it is super heated by the lightening.

What I saw on this night along with many others here in North Texas and Southern Oklahoma were LOTS of lightening with miminal thuder NOT matching the intensity of the lightening.

We saw lightenig 'bolts', 'balls', and 'flashes':

-My neighbor from 2 houses down claims to have SEEN a lightening 'bolt' hit a tree in his back yard, and yet that it made no sound. 'I' should have heard something THAT close, but didn't...

-The 'balls' I saw weren't spherical, but rather lightening bolts spiraling overtop of themselves. Sometimes a bolt would make one spiraled circle, and then bolt over to another area and make another lightening 'ball'.

-These 'balls' and 'bolts' were all the forground for continous 'flashes' of varying brightness throughtout the cloud bank. Sometimes these fashes were small and independent, while other seemed to make the ENTIRE sky white with brightness, often causing the street lights to reset.

But again...

The only thunder was an occasional 'crack', or a very close 'rumble', but none was what I could decipher as being 'associated' with the lightening.

The best explaination was that 'wind' could have been the biggest factor except that there was almost NONE of it to be witnessed.

No trees swaying, no loud wind.

This was a strange thunderstorm, indeed. The last I saw anything similiar was an F-3 tornado I sheltered through in Lawton Oklahoma.
 
Re: I have...

King of the Americas said:
.My neighbor from 2 houses down claims to have SEEN a lightening 'bolt' hit a tree in his back yard, and yet that it made no sound. 'I' should have heard something THAT close, but didn't...
Click to expand...

I've seen television footage that suggested a tree that is hit by lightning has its bark explode off the trunk like shrapnel. Then it possibly goes on fire.

I'd guess the tree would be in pretty bad shape. Maybe your neighbour is mistaken and it was a distant strike if the tree looks okay.
 
Nope...

...the tree wa split down the middle, and had to be removed. 'I' saw the burn marks at the top of the split, and asked "Did that happen the other night? I think I should have heard something that close!"

And my neighbor remarked, "I saw the damn thing hit, and I didn't hear anything!"

But he further added, "Well I DID hear the thing (the TREE) crack and split, but I expected it t be much louder."

I do't think I have EVER seen a tree 'exploded' or 'blown apart' by lightening...
 
This television programme seemed to suggest that parts of the bark shot out in all directions. You'd find little bits of it all around the tree.

A completely different possible explanation for silent lightning that occured to me a few days ago is that perhaps in most cases the air heated by the lightning has a supersonic rate of expansion (and you get a big sonic boom) but in rare cases there are thunder(?)storms producing lightning that gives the heated air a subsonic rate of expansion and relatively little or no sound.

I mean something like the way air is disturbed by fast planes such as concorde or a fighter jet and why such planes aren't allowed to fly faster than the sound barrier (and therefore make sonic booms) over populated areas. Fly over a certain speed and they make a loud boom, fly just under it and there is just a fairly quiet and distant sound.

So perhaps rare atmospheric conditions sometimes allow thunderstorms to produce lightning that doesn't make the air expand faster than a particular rate that is needed to produce a loud shockwave like thunder. If the rate of air expansion for most lightning has values not far above the speed of sound (or some other value that produces the shockwave for lightning) then maybe this idea would be the answer.

If correct, I hereby demand this principle be named after me. :D
 
The thunder I did hear...

...was sparse, and consisted of 'broken cracks that didn't finish'...

...and, the rumble sounded a lot like someone waving a big piece of sheet metal...

...but neither were what I would deem associated with the lightening.

If this sounds strange or unusual, it's because it WAS.
 
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