The sound of expansion

Motor Daddy

Valued Senior Member
This morning as I sat at my computer desk reading the forum the sun appeared once again!!! While reading my favorite guy's postings I heard a CRACK! It was the sun that caused the glass in my window to start heating up, and at some point the expansion force "snapped" which I interpreted as a loud CRACK! Can someone explain that crack to me?

...Is there any possibility that what causes that crack is somehow linked to what causes thunder, just on a smaller scale?
 
This morning as I sat at my computer desk reading the forum the sun appeared once again!!! While reading my favorite guy's postings I heard a CRACK! It was the sun that caused the glass in my window to start heating up, and at some point the expansion force "snapped" which I interpreted as a loud CRACK! Can someone explain that crack to me?

In general the sounds from something heating up is due to the expansion being held back. The stresses increase until it overcomes whatever is pinning or holding back the expansion and the sudden movement cause a sound.

...Is there any possibility that what causes that crack is somehow linked to what causes thunder, just on a smaller scale?

No. The cause of thunder is lightning. The intense heat from the lightning cause the almost instantaneous expansion of air around the spark causing the thunder. For example when you walk across a carpet in your socks and then ground yourself by touching the doornob you get a static shock and hear a little tiny crack - that is small scale thunder.
 
In general the sounds from something heating up is due to the expansion being held back. The stresses increase until it overcomes whatever is pinning or holding back the expansion and the sudden movement cause a sound.



No. The cause of thunder is lightning. The intense heat from the lightning cause the almost instantaneous expansion of air around the spark causing the thunder. For example when you walk across a carpet in your socks and then ground yourself by touching the doornob you get a static shock and hear a little tiny crack - that is small scale thunder.
I have to agree. The sound of thunder is caused by lightening:
http://www.loc.gov/rr/scitech/mysteries/thunder.html

Thunder is caused by the rapid expansion of the air surrounding the path of a lightning bolt.

From the clouds to a nearby tree or roof, a lightning bolt takes only a few thousandths of a second to split through the air. The loud thunder that follows the lightning bolt is commonly said to come from the bolt itself. However, the grumbles and growls we hear in thunderstorms actually come from the rapid expansion of the air surrounding the lightning bolt.
 
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