Question

[CG6468]

When a plane breaks the sound barrier, is the resulting loud BOOM from the plane's engines, or would it be the same without the engine noise?

[ExGeeEye]

It's the shock wave from the speed of the aircraft.

The space shuttle's re-entry was an unpowered glide (no engine noise at all), and was marked by a double sonic boom.  Someone else will have to explain the "double" part, cuz I done fergitted.

[TVDOC]

This is a fairly good explanation:

When an object passes through the air it creates a series of pressure waves in front of it and behind it, similar to the bow and stern waves created by a boat. These waves travel at the speed of sound, and as the speed of the object increases, the waves are forced together, or compressed, because they cannot get out of the way of each other, eventually merging into a single shock wave at the speed of sound. This critical speed is known as Mach 1 and is approximately 1,225 km/h (761 mph) at sea level and 20 °C (68 °F). In smooth flight, the shock wave starts at the nose of the aircraft and ends at the tail. Because radial directions around the aircraft's direction of travel are equivalent, the shock forms a Mach cone with the aircraft at its tip.

There is a rise in pressure at the nose, decreasing steadily to a negative pressure at the tail, followed by a sudden return to normal pressure after the object passes. This "overpressure profile" is known as an N-wave because of its shape. The "boom" is experienced when there is a sudden change in pressure, so the N-wave causes two booms, one when the initial pressure rise from the nose hits, and another when the tail passes and the pressure suddenly returns to normal. This leads to a distinctive "double boom" from supersonic aircraft. When maneuvering, the pressure distribution changes into different forms, with a characteristic U-wave shape.

Since the boom is being generated continually as long as the aircraft is supersonic, it fills out a narrow path on the ground following the aircraft's flight path, a bit like an unrolling red carpet and hence known as the "boom carpet". Its width depends on the altitude of the aircraft. The distance from the point on the ground where the boom is heard to the aircraft depends on its altitude and the angle .

doc

[CG6468]

Thanks. I thunk so but wasn't sure.

[TVDOC]

Thanks. I thunk so but wasn't sure.

No problem.....we actually experience the same phenomena during lightning strikes.......when a lightning discharge occurs the passage of the immense amount of electrical energy displaces the atmosphere along the path of the discharge.  When the current flow stops, the air rushes back in to normalize the pressure, creating a similar shock wave......known as thunder.......

doc

[CG6468]

No problem.....we actually experience the same phenomena during lightning strikes.......when a lightning discharge occurs the passage of the immense amount of electrical energy displaces the atmosphere along the path of the discharge.  When the current flow stops, the air rushes back in to normalize the pressure, creating a similar shock wave......known as thunder.......

doc

I did know that, Doc. (Life is a wonderment....)   

[vesta111]

I did know that, Doc. (Life is a wonderment....)   

Then the question of why earthquakes make a booming sound.

We have had a few small earth quakes that have caused the police to respond to neighboring towns due to the BOOM sound and a few homes have shaken and had very small damage.  Strange but as people call the police over the noise, it is only 2-3 homes effected and the next door neighbors never felt a thing.

Interesting question for me for the last 5+ years.    Police scanner reported dozens of calls about a huge bombing sound, the police went down a road with just a show of lights to see if this was a prank of some kind.  Nothing was found but 3 miles away 4 homes had been damage to their foundations. not adjacent but sort of random in a one block area.

What the heck was this, the area with the damaged homes had not heard no Booms, just the house shake.     The Area that had heard the Booms had no damage.

Local papers said there had been a very small earth quake,  we Yankees do not believe a word of this, Yes we are built on Granite rock but, we also know there are huge areas full of 200 years of garbage that can get crazy with methane  if not vented properly.

Sonic booms have a reason, the same kind of booms coming out of nowhere are another thing.   
 

[DumbAss Tanker]

That's the sound of the mountain dwarves bowling and scoring a strike.  I thought everyone knew that. 

[Eupher]

That's the sound of the mountain dwarves bowling and scoring a strike.  I thought everyone knew that. 

I always thought that "booms" came out of John Lee Hooker.

When he was alive, of course. 

[captrandom]

dumbass question here      

Do sonic booms sound like thunder, or are they more dramatic?

me = 

[chitownchica]

That's the sound of the mountain dwarves bowling and scoring a strike.  I thought everyone knew that. 

I remember being particularly scared during a thunderstorm when I was a wee lass.  My mother said it was the angels bowling, and from that point on, I was never afraid . 

[thundley4]

I remember being particularly scared during a thunderstorm when I was a wee lass.  My mother said it was the angels bowling, and from that point on, I was never afraid . 

I had always heard it was God unloading a big sack of potatoes .

[DumbAss Tanker]

I had always heard it was God unloading a big sack of potatoes .

Well, I suppose that sounds less scary to a kid than to tell him it's the sound of God emptying a dumptruck load of doomed souls over the side of the clouds, sure...

 

[chitownchica]

I had always heard it was God unloading a big sack of potatoes .

That's a good one too  .

[vesta111]

As a kid we were taught to count, still do to find out how far away a lightening display is from us.

See the lightening and count the seconds before the boom, each second was approximately one mile away.

Allot of old wives tales that may in fact be true, some people draw lightening, some have been hit 3-4 times while others next to them escape.

Had a strange encounter with a storm just ONCE--the huge tree in the front yard late at night was hit some how.    The Boom awakened me and all the hair on my body was standing straight up.   The bedroom had a flash of blue light.

Neighbors came running but we could see no damage---until---2 days later when all the leaves on this beautiful tree died.     Then the older big limbs began to fall.

I was renting a house at the time and called the landlord and he tried to blow me off with a what can I do until I mentioned that the large tree had branches over hanging the street and a falling limb could kill someone walking by.

Out come the tree cutters that told me the tree was not hit from above but the energy came from the ground up. The tree was not hit from electricity in downward but from electricity traveling up through the tree to the sky.

Never heard of this before but as the tree cutters told me, there had to have been some kind of magnetism in play.

Lots of strange stuff and warnings about lightening and thunder.  Something is traveling faster then the sound of speed to make the boom????

Off topic, I wonder what would happen were we to invent something that goes faster then the speed of light???????

[TVDOC]

As a kid we were taught to count, still do to find out how far away a lightening display is from us.

See the lightening and count the seconds before the boom, each second was approximately one mile away.

Allot of old wives tales that may in fact be true, some people draw lightening, some have been hit 3-4 times while others next to them escape.

This kinda illustrates just how horribly wrong relying on "old wives tales" can be...........let's do the simple arithmetic.....one mile is 5280 feet (statute).

Since the speed of sound at sea level is approximately 1116 feet per second, counting seconds from a lightning flash until the thunder clap would more accurately be 5 seconds to a mile........

doc