Earth’s atmosphere is ringing like a bell

Let the atmospheric music play on!


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A recent study by scientists at Kyoto University and the University of Hawai’i at Mānoa shows that the Earth’s entire atmosphere vibrates analogously.

In the case of the atmosphere, the “music” comes not as a sound we could hear; instead, it is in the form of large-scale waves of atmospheric pressure spreading over the globe and traveling around the equator, some moving east-to-west and others west-to-east. Every one of these waves is a resonant vibration of the global atmosphere, practically equivalent to one of the resounding pitches of a bell.

In a new study, scientists present a detailed analysis of observed atmospheric pressure over the globe every hour for 38 years. The results revealed the presence of dozens of the predicted wave modes.

Animation of pressure patterns for four individual wave modes.

Scientists mainly focused on waves with periods between 2 hours and 33 hours, which travel horizontally through the atmosphere, moving all around the world at great speeds (surpassing 700 miles per hour). This sets up a characteristic “chequerboard” pattern of high and low weight related to these waves as they propagate.

Lead author Takatoshi Sakazaki said, “For these rapidly moving wave modes, our observed frequencies and global patterns match those theoretically predicted very well. It is exciting to see the vision of Laplace and other pioneering physicists so completely validated after two centuries.”

Checkerboard pattern of pressure
A checkerboard pattern of low (blue) and high (red) pressure areas moving eastward through time, generated by just two of the ringing vibrations of the global atmosphere (periods = 32.4 hrs and 9.4 hrs). Credit: Sakazaki and Hamilton

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, said, “Our identification of so many modes in real data shows that the atmosphere is indeed ringing like a bell. This finally resolves a longstanding and classic issue in atmospheric science. Still, it also opens a new avenue of research to understand both the processes that excite the waves and the processes that act to damp the waves.”

Journal Reference:
  1. Kevin Hamilton et al. An Array of Ringing Global Free Modes Discovered in Tropical Surface Pressure Data. Journal of the Atmospheric Sciences. DOI: 10.1175/JAS-D-20-0053.1


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