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Atmospheric tides alter rainfall rate

Pressure changes from moon’s gravity affect weather, but imperceptibly

11:24am, January 19, 2016
lunar tides

HIGH TIDE  The moon’s position imperceptibly affects rainfall on Earth, new research shows. The lunar gravity generates atmospheric tides that raise and lower atmospheric pressure, slightly altering rainfall rates, researchers propose.

When you see a bad moon rising, expect an ever-so-slightly wetter day. The lunar gravitational pull imperceptibly boosts rainfall when the moon is on the horizon and somewhat reduces rainfall when the moon is overhead or on the opposite side of the Earth, a new analysis of global rainfall concludes.

The cause is the atmospheric equivalent of ocean tides, researchers propose in a paper to be published in Geophysical Research Letters. Air gathers on Earth’s moon-facing side and on the opposite end of the globe. Scientists noticed that this pileup increases atmospheric pressure and predicted that atmospheric tides could alter precipitation rates as well. Scouring 15 years of global precipitation data, the researchers have discovered that the effect is present, but tiny: an approximately one micrometer per hour change in rainfall rate.

“No one should carry an umbrella just

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