Behind the Forecast: Can the moon impact our weather?
Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
LOUISVILLE, Ky. (WAVE) - The sun substantially impacts our weather, but did you know that the moon can influence the forecast too?
The moon’s most evident impact comes in the form of ocean tides. As the Earth rotates daily, the moon’s gravity pulls on the water on the side of the planet closest to it. The ocean also bulges on the opposite side of Earth due to its rotation. These bulges result in the two low and high tides seen each day.
The moon’s orbit has its own cycle (the lunar nodal cycle). It wobbles every 18.6 years between a minimum and maximum of plus or minus five degrees relative to the Earth’s equator. When the moon’s orbit aligns with the equator, tides become exaggerated and grow smaller as the moon tilts away.
The tides impact global ocean currents. Warm ocean currents lead to warm, wet weather, while cold ocean currents lead to drier, colder weather.
The El Nino-Southern Oscillation (which encompasses the El Nino and La Nina) is a perfect example of how ocean currents can influence global weather. During an El Nino, trade winds along the equator that usually push warm surface water from South America towards Asia weaken and sometimes reverse. Warm water collects near the western South American coast leading to wetter winters in the southern United States and warm, drier conditions further north. A La Nina leads to colder water off of the South American coast due to stronger trade winds. La Nina winters are typically warmer than average across the southern US and cooler further north.
Some researchers have suggested that the lunar tidal gravitational force may influence the switch between El Nino and La Nina.
The moon may also influence polar temperatures and the extent of Arctic ice. Satellite measurements show that the poles are 0.99 degrees Fahrenheit warmer during a full moon compared to a new moon, potentially due to the amount of light it reflects. While temperature change isn’t great, it could impact the weather.
The moon’s gravitational forces also have a slight tug on the earth’s atmosphere. The impact is less than what’s seen on the ocean tides. The bulges in the atmosphere lead to an increase in air pressure which in turn increases the temperature. Since warmer air holds more moisture, lower rainfall is seen according to one study. This impact on rainfall is minimal. Scientists have only found about a one percent variation in rainfall due to changes called by the moon.
The moon helps to steady the earth’s rotation, stabilizing the atmosphere. While its impact may not always be great, it still plays a significant role in life here on our planet.
Copyright 2022 WAVE. All rights reserved.