Why does the sky rumble during a thunder storm?

Question

I know how lightening is produced.

Answer 1

it is the sound waves produced by the electic discharge.

In a fraction of a second the air is heated to a temperature approaching 28,000 °C (50,000 °F) by lightning. This heating causes it to expand outward, plowing into the surrounding cooler air at a speed faster than sound would travel in that cooler air. The outward-moving pulse that results is a shock wave, similar in principle to the shock wave formed by an explosion, or at the front of a supersonic aircraft.

The gentle rumbles are you hearing those explosions in are ripple effect the further away you are the less the sound is. The closer the storm is to you the louder the boom is. Imagine a stone into a puddle. The ripples go outwards, now drop another onto the same puddle and the rings overlap. If you were listening to sound waves instead of watching water waves you would have the same effect. Depending on where you are in relation to the expansion of the air and shockwave it produces you either hear a loud bang or a subtle rumble.

Answer 2

The acoustic radiation produced by thermal lightning channel processes. The lightning return stroke is a high surge of electric current that has a very short duration, depositing approximately 95% of its electrical energy during the first 20 microseconds. Spectroscopic studies have shown that the lightning channel is heated to temperatures in the 20,000–30,000 K (36,000–54,000°F) range by this process. The pressure of the hot channel exceeds 10 atm (>106 pascals). The hot, high-pressure channel expands supersonically and forms a shock wave as it pushes against the surrounding air. Because of the momentum gained in expanding, the shock wave overshoots, causing the pressure in the core of the channel to go below atmospheric pressure temporarily. The outward-propagating wave separates from the core of the channel, forming an N-shaped wave that eventually decays into an acoustic wavelet. See also Shock wave; Storm electricity.

The sound that is eventually heard or detected, thunder, is the sum of many individual acoustic pulses, each a remnant of a shock wave, that have propagated to the point of observation from the generating channel segments. The first sounds arrive from the nearest part of the lightning channel and the last sounds from the most distant parts.

The higher the source of the sound, the farther it can be heard. Frequently, the thunder that is heard originates in the cloud and not in the visible channel. On some occasions, the observer may hear no thunder at all; this is more frequent at night when lightning can be seen over long distances and thunder can be heard only over a limited range (∼10 km or 6 mi).

Answer 3

http://www.srh.noaa.gov/srh/jetstream/lightning/thunder.htm
(See Link for Visual Presentation)

Regardless of whether lightning is positive or negative, thunder is produced the same way. Thunder is the acoustic shock wave resulting from the extreme heat generated by a lightning flash. Lightning can be as hot as 54,000°F (30,000°C), a temperature that is five times the surface of the sun! When lightning occurs, it heats the air surrounding its channel to that same incredible temperature in a fraction of a second.

Like all gases, when air molecules are heated, they expand. The faster they are heated, the faster their rate of expansion. But when air is heated to 54,000°F in a fraction of a second, a phenomenon known as "explosive expansion" occurs. This is where air expands so rapidly that it compresses the air in front of it, forming a shock wave similar to a sonic boom. Exploding fireworks produce a similar result.




When lightning strikes a shock wave is generated at each point along the path of the lightning bolt. (The above illustrations show only four points.)
With nearby lightning strikes the thunder will sound like a loud bang, crack or snap and its duration will be very short.
As the shock wave propagates away from the strike center, it stretches, diminishes, and becomes elongated. Then other shock waves from more distance locations arrive at the listener.
At large distances from the center, the shock wave (thunder) can be many miles across. To the listener, the combination of shock waves gives thunder the continuous rumble we hear.
Learning Lesson: Determining distance to a thunderstorm

In addition, the temperature of the atmosphere affects the thunder sound you hear as well as how far away you can hear it. Sound waves move faster in warm air than they do in cool air. Typically, the air temperature decreases with height. When this occurs, thunder will normally have an audible range up to 10 miles (16 km).

However, when the air temperature increases with height, called an inversion, sound waves are refracted (bent back toward the earth) as they move due to their faster motion in the warmer air. Normally, only the direct sound of thunder is heard. But refraction can add some additional sound, effectively amplifying the thunder and making it sound louder.

This is more common in the winter as thunderstorms develop in the warm air above a cooler surface air mass. If the lightning in these "elevated thunderstorms" remains above the inversion, then most of the thunder sound also remains above the inversion. However, much of the sound waves from cloud-to-ground strikes remain below the inversion giving thunder a much louder impact.

Answer 4

Thunder is caused by the rapid expansion and contraction of air surrounding lightning bolts. Since a lightning bolt is 5 times hotter than the surface of the sun all the air around it super heats and expands. It doesn't expand for long, however, and quickly contracts. When THIS happens (the contraction of the air) THAT causes sound waves.... like little ripple tides in a lake after you throw in a rock---- and these waves result in sound to your ear. Rumble on.

Answer 5

Thunder is one of the few things that can break down Nitrogen ions. When thunder is produced, the result of the seperation of the triple bonded nitrogen ions causes a large amount of sound to be produced.

Answer 6

Because Henry Hudson and the gnomes are playing nine-pins in the Catskills.

Answer 7

You know about lightening, do you know about echo and reverberation? See below.

Answer 8

Because the norse god 'Thor' is shouting with anger.