Music in The Clouds

In June 1867, James Glaisher, an English astronomer and meteorologists, and an avid balloonist, was floating over Paris in a balloon when he entered a region of dense cloud:

Suddenly, whilst we are thus suspended in the misty air, we hear an admirable concert of instrumental music, which seems to come from the cloud itself and from a distance of a few yards only from us. Our eyes endeavour to penetrate the depths of white, homogeneous, nebulous matter which surrounds us in every direction. We listen with no little astonishment to the sounds of the mysterious orchestra.

This wasn’t the first time Glaisher had heard music when flying through clouds. Five years earlier, Glaisher had taken off in a balloon from Wolverhampton city in England. At an elevation of 12,700 feet, he clearly heard a band of music playing.

In 1867, Glaisher, along with other balloon enthusiasts, notably, Camille Flammarion—a French astronomer, and Gaston Tissandier—a French meteorologist, began a series of experiments with balloon flights, and over two days, flew from Paris to Solingen, near Cologne. Glaisher mentions hearing music and various sounds several times during this trip, while floating above the ground at thousands of feet. “We were serenaded by some excellent orchestral music whilst sailing over Antony and over Boulainvilliers; we were then entirely enveloped by clouds, and about 3,280 feet above each of those towns.”

Glaisher wrote on his memoirs of balloon flight, Travels in the Air:

I find that the intensity of various sounds emitted at the surface of the earth is carried up to very great heights in the atmosphere. The whistle of a locomotive rises to near 10,000 feet, the noise of a railway train to 8,200 feet, the barking of a dog to 5,900 feet; the report of a musket is heard to about the same height; the shouting of men and women can be heard sometimes as high as 5,000 feet, and at this altitude the crowing of a cock and the sound of a church bell are audible. At a height of 4,550 feet the roll of a drum and the music of an orchestra are distinctly heard. At 3,255 feet in altitude, a man's voice may make itself heard; the rolling of a cart on the pavement can be distinguished somewhat higher; and in the stillness of the night the course of a river, or even that of a small stream, produces at this elevation almost the effect of a high waterfall. At a height of 3,000 feet the croaking of frogs in a morass is heard in all its intensity, and even the sharp note of the mole-cricket is distinguished easily at an altitude of 2,500 feet.

What Glaisher and his companions experienced was the effect of humidity on sound level. It has been observed that as humidity increases the sound level also rises. Clouds and fog being more humid “collects sound with such intensity,” explains Glaisher, “that whenever, in passing through a cloud, we have heard a band playing in a town beneath us, the music always seemed to be close at hand.”

“Lower humidity absorbs more sound, especially at higher frequencies, because of "molecular relaxation" in the gases in the air (a level of 10% humidity absorbs the most),” explains NPS. “A substantial change in atmospheric pressure, equivalent to thousands of feet of elevation gain, has a small influence on noise level for most sources, but substantially affects the received levels of those sounds.”