When the moon is high in the sky, it creates bumps in the planet’s atmosphere that in turn generate almost imperceptible changes in the amount of rain that subsequently falls. Thus, new research carried out by scientists at the University of Washington (USA) reveals the influence – albeit slight – of the phases of the Moon on rain.
“As far as I know, this is the first study that convincingly connects the moon’s tidal forces with rainfall,” says study leader Tsubasa Kohyama.
The researchers were studying atmospheric waves when they noticed a slight oscillation in air pressure ; After two years of tracking this phenomenon, they discovered that these pressure changes, as well as the temperature, were linked to lunar forces . To confirm that air pressure at the surface did indeed vary with the phases of the Moon, the scientists used a global data grid throughout the duration of the study, which they collated against a 15-year NASA database and data on tropical rainfall collected by the Japan Space Exploration Agency.
When the moon is highest in the sky , the air pressure is higher. This happens because the gravity of the Moon causes the Earth’s atmosphere to bulge towards it, so the weight of the atmosphere on that side of the planet rises . Higher pressure also causes the air temperature to rise. As the air is warmer, it can also contain more humidity and therefore be further away from its relative humidity capacity .
“It is as if the container gets bigger with higher pressure. Relative humidity affects rain, because lower humidity is less favorable for precipitation, ”explains Kohyama.
Specifically, the rain is 1% lighter when the moon is high . “No one should carry an umbrella just because the moon is high,” explains Kohyama, but this data could be used to test climate models and further explore whether the frequency of storms shows any lunar connection.
The study has been published in the journal Geophysical Research Letters .
