A team of researchers from the University of Washington have made a fascinating discovery about the effects of the moon’s phase on the planet’s weather. According to a report from Phys.org, researchers have shown that when the moon is high in the sky, it makes bulges in the atmosphere that affect the levels of rainfall around the globe.

The study, published in the journal Geophysical Research Letters, reveals that while the moon’s effect on rainfall is imperceptible on the ground, a look at the bigger picture tells a different story.

As far as I know, this is the first study to convincingly connect the tidal force of the moon with rainfall,” said co-author Tsubasa Kohyama, an atmospheric sciences doctoral student at the University of Washington.

Kohyama and his co-author, John Michael Wallace, a professor of atmospheric sciences at the University of Washington, have been studying these atmospheric bulges for a long time. They first noticed minute oscillations in air pressure when they were studying atmospheric waves, and spent the better part of two years trying to figure out what could possibly be causing it.

The researchers turned to previous studies that had linked air pressure to lunar phases as early as 1847. Scientists had established that air pressure was influenced by lunar forces, but what about rainfall?

The new study shows that the moon’s gravitational forces also have an affect on precipitation. When the moon is high in the sky, the gravity compresses the Earth’s atmosphere towards the surface. As the bulge creates a pocket of higher air pressure, the air particles begin to warm up and subsequently can carry more moisture. When the clouds in the bulge have reached a saturation point, unable to hold more water vapor, it begins to rain.

“It’s like the container becomes larger at higher pressure,” said Kohyama. As the air becomes warmer and more humid, it increases the chances of rain. While a full moon is no guarantee that it’s going to rain soon, the new study shows that it still may have something to do with wet weather.

A press release from the University of Washington describing the details of the study can be found here.