Back in my ill spent youth, every one told us to count seconds from the flash, then 5 seconds was equal to a mile. 15 seconds was 3 miles, or thereabouts.

But we see flashes that never touch the ground (cloud to cloud) or flashes that light up the entire sky. So I assume the flash we see is for the entire length of the strike at the same instand, but only hear the thunder for the closest part. How does altitude impact that? Would a 15,000 foot strike be the same as one 3 miles out?

I have an App on my phone, 'Thunder and Lightning' I think it was free. You can hit the button when you hear thunder or a button for lightning and it will tell you how far away it is.

5280/1125 =4.69 seconds = 1 mile.

Higher up speed of sound is slower.

Better yet, go to www.lightningmaps.org and see a live map of lightning strikes based on data from an international network of lightning detection stations. (Yes, really! Sounds crazy, right?)

New strikes are yellow and have a red ring around them. The red ring disappears after maybe 30 seconds, then the strikes fade from yellow to orange to brown over the course of a couple of hours.

They also draw expanding circles showing the sound of the thunder from the strike moving across the map.

(Make sure to click on the "Real Time" map, not the "America" map.)

There's typically a delay of a few seconds between real life and the map. Right now it's showing up as 3 seconds for me (it gives you the current delay in the corner of the map).

quote:

Originally posted by Skins2881:
5280/1125 =4.69 seconds = 1 mile.

Higher up speed of sound is slower.

The speed of sound varies with temperature, not altitude. But at higher elevations the temperature is usually lower and therefore so too is the speed of sound.

See here.

Driving north through Slower Lower on a half-sunny / half-thunderstormy afternoon, I happened to gaze across a green field when BAM, as explosion rocked my truck.

It was a burst of lightening about 40'- 80' off the ground. It looked as big as a VW bug, but at that distance, it may have been as big as a panel truck.

I think I saw a genuine base of the lightening arc. There were tatters of black soot drifting from the explosion, like the air itself was burnt.

Hate to bave been the conductor of ground to the atmosphere's charge on that one! Talk about burnt microwave popcorn!

WeatherBug app has a lightning distance feature.
Gives you a warning when lightning is within 10 miles or so.
Distance to closest lightning strike is always shown, today it was 700 miles.
Their maps show lightning strikes as they occur, as does other similar apps.

WeatherBug app has a lightning distance feature.
Gives you a warning when lightning is within 10 miles or so.
Distance to closest lightning strike is always shown, today it was 700 miles.
Their maps show lightning strikes as they occur, as does other similar apps. You can zoom in, see your house and the strikes that have occurred.
Of course when you see the flash, and the thunder boom occurs at the same time, with your house rattling, you know it was close and maybe time to clean your pants?

quote:

Originally posted by sigfreund:

quote:

Originally posted by Skins2881:
5280/1125 =4.69 seconds = 1 mile.

Higher up speed of sound is slower.

The speed of sound varies with temperature, not altitude. But at higher elevations the temperature is usually lower and therefore so too is the speed of sound.

See here.

Huh, learn something new every day. I figured to more dense air is the faster sound would travel through it, except that the increase in pressure slows sound down by the same amount. Pressure and density vary the same amount by altitude and their individual affects on the speed of sound cancel each other out.

Stand outside with the phone to your ear while talking. It's like playing tag with God, if you see and hear the flash/noise at the same time - you're it!!

One hippopotamus, two hippopotamus....

I use the same site as maladat. I work in a mine and we sometimes have charged blasting patterns, when lightning is present, it's nice to know how close it is so we can get far enough away to be safe...

If you hear the sound, and then see the flash, you're too close.

quote:

Originally posted by sigmonkey:
If you hear the sound, and then see the flash, you're too close.

And you didn't win Powerball!

I always equated each second between lightning flash and thunder clap to one mile.

One sure thing...if you can see this guy, you're too close

Used to be one Mississippi two Mississippi, each Mississippi was a mile away..Who needs technology.:-)

I wave a 10 foot piece of conduit around

quote:

Originally posted by sigfreund:

quote:

Originally posted by Skins2881:
5280/1125 =4.69 seconds = 1 mile.

Higher up speed of sound is slower.

The speed of sound varies with temperature, not altitude. But at higher elevations the temperature is usually lower and therefore so too is the speed of sound.

See here.

You are both correct; higher altitude means less dense air, which is dependent on air temperature. For an ideal gas the speed of sound is proportional to the square root of the absolute temperature.

From the website you quoted:
"The speed of sound is dependent on the density of the air...and the density of the air is dependent on the temperature of the air."

all I know is that a former room mate was stationed on the island off t he coast of California.

his job was to listen to the ocean and identify
craft that were more than 100 miles off shore
through the use of underwater microphones.

I imagine computers do all of the recognizing / identifying these days