Just as the Moon affects the oceans of our planet, contributing to the ebb and flow, it also pulls our atmosphere, creating waves in the skies.
The new study demonstrates how certain types of "celestial waves" resonate around the Earth, much like how sound waves resonate inside a bell.
In water, waves are generated by the passage of energy. The energy moving across our sky is from things like heat pressure and the gravitational pull of heavenly bodies.
Previous research has focused on localized spaces and limited time scales, which has enabled the detection of waves 1,000 to 10,000 km wide with wave frequencies of several hours. But recent data has opened up a much broader global view.
The ERA5 dataset, produced by the European Center for Medium-Range Weather Forecasts (ECMWF), provides hourly real-time estimates of many global climate variables for the atmosphere, land and ocean. The data also contains a ton of re-analyzed historical observations of these measurements, up to 1979.
This allowed Takatoshi Sakazaki of the University of Kyoto and Kevin Hamilton of the University of Hawaii to explore 38 years of atmospheric pressure data, including celestial waves with frequencies ranging from 2 hours to 2 days and wavelengths over 5,000 km.
At this scale, the researchers were able to detect: "randomly excited resonant modes of a global scale", first predicted in the 19th century by the famous French physicist Pierre-Simon Laplace.
If waves travel through the air at the right height and speed, they can harmonize with the atmosphere, creating resonance. This allows the waves to form a pattern stable enough to vibrate throughout the global atmosphere, like sound waves from a bell.
Indeed, the researchers discovered sets of these resonating celestial waves (resonant modes) that swept the entire globe, introducing tonal layers into the bell-shaped sounds of the atmosphere.
“Our identification of so many modes in real data shows that the atmosphere is indeed ringing like a bell,” Hamilton said.
