Moon Directly Affects Rainfall Amounts On Earth, Say Scientists

The moon has enraptured mankind for thousands of years. The earliest civilizations thought of the moon as an entity or deity, benign or malign. The ancient Mayans thought of the moon as a goddess, and her phases coincided with the phases of a woman’s cycle. The Greeks also thought of the moon as a goddess, naming her Selene. The ancient Egyptians called the moon, “Eye of Ra,” to be the enforcer for the Sun, (Ra), seeing her as a violent entity to be loosened on Ra’s enemies.

No matter how humans have thought of the moon through the ages, it’s clear that our lone natural satellite has always had an effect on us as a species. Of course, the moon has always had an effect on the Earth as well. The moon’s gravity affects the tides in the world’s oceans, pulling at the water on whatever side of the Earth is closest to the moon at the present time. Now, however, scientists have discovered another incredible impact the moon has upon the Earth: it directly impacts the rainfall we experience here on our planet.

Moon affects rainfall
[Photo by Kevin Frayer/Getty Images]

A new study from the University of Washington states that the Moon creates atmospheric bulges that in turn result in changes to rainfall.

A co-author of the study, Tsubasa Kohyama, said that this study was the first one in the history of mankind to “convincingly connect the tidal force of the moon with rainfall.”

Kohyama and his fellow study author from the University of Washington, Professor John Wallace, spent two years studying the links between the moon’s gravity and rainfall. They first started taking notice when Kohyama observed oscillation in the air pressure when he was studying atmospheric waves. The oscillation coincided with the moon’s position around the Earth.

Whenever the moon is overhead or “underfoot,” the resulting air pressure is higher, which then results in lighter rainfall. When the moon is directly overhead, the atmosphere “bulges” outward in that direction from the moon’s gravity, resulting in the atmospheric pressure on the corresponding side of Earth to go up. That higher atmospheric pressure makes air parcel temperature hotter, and since warmer air is capable of holding greater moisture, that affects the chances of rainfall, because lower humidity is less likely to produce precipitation.

So what does all this mean? Is there some way we can manipulate the moon to influence rainfall? Is there some way we can predict rainfall via the position of the moon around the Earth? Sadly, in the end, the conclusion on its own that the moon does affect rainfall on the Earth doesn’t really amount to much. Why? For one thing, the influence that the moon exudes on the Earth in regards to rainfall is actually very small. According to the scientists, there is only about a 1 percent variation on total rainfall on the entire planet that is actually affected by the gravity of the moon. However, the scientific study is just that: a scientific study. Many studies, like this one that links the phases of the moon to a change in rainfall amounts, don’t mean much on their own. However, they do expand our knowledge of the way one minute part of the universe works, and the grand collective of all that information can only add to our understanding of the universe itself.

Moon affects Earth's Rainfall
[Photo by Mario Tama/Getty Images]

So, does all this mean that the moon isn’t important? Is it just some rock that’s out there, some big stone whose reflection offers us a bit of light on a dark night? No. The moon is much more important than that. The moon is locked in a cosmic attraction with the Earth, and without it, we would be in terrific trouble. One small example of how life we know on Earth would change if we had not moon is that the Earth would inevitable change the tilt on its axis often, the same way a spinning top changes its nutation over time. The moon holds us in a relative position, so that the tropics don’t suddenly become the poles and vice versa.

The recent study about the moon was published in Geophysical Research Letters.

[Photo by Rick Diamond/Getty Images for Sound Harvest Music Festival]