A. Lightning parts the air through which it passes; and when the parted air closes again, the noise made by the concussion, is called Thunder.
Q. Why does lightning part the air through which it passes? It does not part a rod of iron.
A. Iron is a conductor, and therefore allows the fluid to go freely through it: but air being a non-conductor, resists the lightning; which, therefore, rips it open, in order to pass through it.
Q. Why is thunder sometimes one vast crash?
A. When the lightning-cloud is near the earth, as the flash is straight,—the whole volume of air (through which it passes) collapses at once; and produces one unbroken sudden crash.
Q. What is meant by the air collapsing?
A. When the rent air closes again, it is said to collapse.
Q. Why is the peal sometimes an irregular mangling broken roar?
A. When the lightning-cloud is a long way off, as the flash is zigzag, the air does not collapse all at once; and as we hear the concussion of one part after another, the peal is broken, protracted, and irregular.