As the moon rises, slight swelling in the atmosphere produces tiny changes in the amount of rainfall, according to research from the University of Washington.
Co-author Tsubasa Kohyama, said, "As far as I know, this is the first study to convincingly connect the tidal force of the moon with rainfall. When the moon is overhead or underfoot, the air pressure is higher."
The study, to be published in the journal Geophysical Research Letters, also suggests a modest dip in the amount of rain due to the moon's gravitational pull.
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A picture taken in Toulouse shows the moon on October 25, 2015. AFP PHOTO / REMY GABALDA (Photo credit should read REMY GABALDA/AFP/Getty Images)
A near full moon is seen over Washington, DC, on October 26, 2015. The moon is in a Waxing Gibbous phase and will be full on October 27th. AFP PHOTO / NICHOLAS KAMM (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
A Brazilian Bororo Indian is seen in front of the moon at the World Indigenous Games, in Palmas, Brazil, Monday, Oct. 26, 2015. Non-indigenous locals from sleepy Palmas, where the Games are the biggest thing ever to roll into the town during its short 27-year history as the capital of Brazilâs newest state of Tocantins, got in on the action, too, filling the bleachers and swarming the handicraft fair, getting body paint tattoos and donning headdresses made from macaws. (AP Photo/Eraldo Peres)
Kansas City Royals' Salvador Perez waits to bat as the near full moon rises in the distance during a baseball workout Sunday, Oct. 25, 2015, in Kansas City, Mo. The Royals will face the New York Mets in Game 1 of the World Series on Tuesday in Kansas City. (A (AP Photo/Charlie Riedel)
PRESHEVO, SERBIA - OCTOBER 26: An almost full moon rises behind a moon crescent on a mosque on October 26, 2015 in Preshevo, Serbia. Despite EU Jean-Claude Juncker warning that thousands of refugees could perish this winter unless a solution to crisis was found, thousands of migrants are continuing daily to pass along the Balkan countries such as Serbia as they make the journey north to more affluent countries in western Europe. (Photo by Matt Cardy/Getty Images)
The moon rises in the sky above Toulouse on the night of October 25, 2015.AFP/ REMY GABALDA (Photo credit should read REMY GABALDA/AFP/Getty Images)
A woman is silhouetted near a window as the moon shines over the International Financial Center or IFC building in Beijing, China, Monday, Oct. 26, 2015. Facing pressure to pep up a cooling economy, Chinese leaders met Monday to craft a new long-range blueprint to guide development through the end of this decade. (AP Photo/Ng Han Guan)
Full moon rises over a chapel next to a vineyard near Bergtheim, southern Germany, on October 26, 2015. AFP PHOTO / DPA / KARL-JOSEF HILDENBRAND +++ GERMANY OUT (Photo credit should read KARL-JOSEF HILDENBRAND/AFP/Getty Images)
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According to a summary of the findings, "When the moon is overhead, its gravity causes Earth's atmosphere to bulge toward it, so the pressure or weight of the atmosphere on that side of the planet goes up. Higher pressure increases the temperature of air parcels below. Since warmer air can hold more moisture, the same air parcels are now farther from their moisture capacity."
The research is based on 15 years of data compiled by NASA and the Japan Aerospace Exploration Agency's Tropical Rainfall Measuring Mission.
And, though the change is measurable, it's not really noticeable—ultimately accounting for only one percent of variation in rainfall.
Kohyama said, "No one should carry an umbrella just because the moon is rising."