A study by scientists at Kyoto University and the University of Hawai'i at Mānoa has shown that the Earth's entire atmosphere vibrates in a manner that greatly resembles the vibrations of a ringing bell.
The study, a detailed analysis of observations taken of the Earth's atmosphere over decades, has been touted as a striking confirmation of theories that have been gradually developed by physicists over the course of the last two centuries.
Atmospheric wave theories
A ringing bell produces its distinct musical sound by vibrating simultaneously at several frequencies: it sounds a low-pitched fundamental tone at the same time as many higher-pitched overtones.
In their study, published in the Journal of the Atmospheric Sciences, the scientists describe a kind of "music" in the atmosphere that isn't detected as a sound we can hear, but rather as large-scale waves of atmospheric pressure that spans the globe and travels around the equator, some moving east-to-west and others west-to-east.
Each of the waves detected by the scientists is a resonant vibration of the global atmosphere that has analogous characteristics to a resonant pitch of a ringing bell.
Much in the same way that the Moon has a gravitational tidal influence that pulls at the Earth's seas, it also pulls at our atmosphere. Along with the Sun's influence, this creates atmospheric waves, or resonances, in the sky that are detectable as moving pockets of tightly packed air that can be thousands of kilometers long.
The study of such atmospheric resonances began in the 19th century with French physicist and mathematician Pierre-Simon Laplace and has gained traction over the subsequent two centuries.
In this time, Laplace's theory was refined, leading to detailed predictions of wave frequencies in the atmosphere. However, the actual detection of these waves has been a challenge scientists have been working hard to overcome.
Confirmation of centuries-old theories
Now, in the new study by Takatoshi Sakazaki an assistant professor at the Kyoto University Graduate School of Science, and Kevin Hamilton, an Emeritus Professor in the Department of Atmospheric Sciences and the International Pacific Research Center at the University of Hawai'i at Mānoa, the researchers have presented a detailed analysis of observations of atmospheric pressure every hour for a staggering 38 years.
The results of the study finally revealed dozens of wave models that had been predicted only in theory.
The study focused on waves with periods between 2 hours and 33 hours. These travel horizontally through the atmosphere, moving at speeds in excess of 1127 km/h (700 miles per hour).
As can be seen in the gif below, these waves create a "chequerboard" pattern of high and low pressure as they propagate around the globe.
"For these rapidly moving wave modes, our observed frequencies and global patterns match those theoretically predicted very well," lead author Sakazaki said in a press release. "It is exciting to see the vision of Laplace and other pioneering physicists so completely validated after two centuries."
The researchers say that not only does their study resolve "a longstanding and classic issue in atmospheric science," it has also opened up a new avenue of research that could allow for the understanding of both of the processes that serve to excite and dampen the waves as they travel around the globe, creating a rich atmospheric music that's waiting to be studied in greater detail.