When the moon is high in the sky, it creates bulges in the planet’s atmosphere that creates imperceptible changes in the amount of rain that falls below.
New University of Washington research to be published in Geophysical Research Letters shows that the lunar forces affect the amount of rain – though very slightly.
“As far as I know, this is the first study to convincingly connect the tidal force of the moon with rainfall,” said corresponding author Tubas Kohyama, a UW doctoral student in the Department of Atmospheric Sciences.
Kohyama was studying atmospheric waves when he noticed a slight oscillation in the air pressure. He and co-author John (Michael) Wallace, a UW professor of atmospheric sciences, spent two years tracking down the phenomenon.
Air pressure changes linked to the phases of the moon were first detected in 1847, and temperature in 1932, in ground-based observations. An earlier paper by the UW researchers used a global grid of data to confirm that air pressure on the surface definitely varies with the phases of the moon.
“When the moon is overhead or underfoot, the air pressure is higher,” Kohyama said.
Their new paper is the first to show that the moon’s gravitational tug also puts a slight damper on the rain.
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