The Scientific American is an excellent journal for those who wish be kept authoritatively up to date on a wide range of scientific topics. As a general rule, however, it is not one in which new findings are announced for the first time; the preferred avenue in such circumstances is publication in one of the more esoteric periodicals where articles are subjected to a "peer review".
But there have been exceptions: in 1888, for example, the Scientific American published an article entitled "The Sound of Thunder" by a French man by the name of Hirn, in which it was satisfactorily explained for the first time why a peal of thunder has such a long, reverberating roll.
Hirn's theory was as follows: "The sound which is known as thunder is due simply to the fact that the air, traversed by an electric spark - that is, a flash of lightning - is suddenly raised to a very high temperature and has its volume, moreover, considerably increased.
"The column of gas thus suddenly heated and expanded is sometimes several miles long, and as the duration of the flash is not even a millionth of a second, it follows that the noise bursts forth at once from the whole column. For an observer in any one place, however, it commences where the lightning is at the least distance.
"The beginning of the thunderclap therefore gives us the minimum distance of the lightning, and the duration of the thunderclap gives us the length of the column."
As Hirn implies, the sound of thunder varies depending on the relative positions of the listener and the thunderstorm. A bolt of lightning follows a jagged zig-zag path that is, in effect, a meandering channel of small, straight segments of superheated air. As the electric current increases the temperature very rapidly, the air throughout the channel expands explosively, and the resulting shock-wave reaches our ears as sound.
Now the successive segments can be thought of almost as a string of beads, with sound emanating simultaneously from each individual bead. Thunder from the "beads" furthest away is not only slower to reach the listener's ear, but it is also modified by the atmosphere; as a result, the noise from the closer beads is heard as a sharp clap of thunder, but that from distant segments, heard later, is also more muffled.
To add confusion to cacophony, sound waves from segments near and far amalgamate while heading towards the listener, so he or she hears something like a near-continuous roll with a variety of sharp cracks and low rumbles interspersed.