A Warm Moon Glow

March 12, 1995|By Cox News Service

Moon glow, it seems, is good for something besides corny lyrics and romance.

Although the idea may sound a little loony at first, scientists have discovered that a full moon not only makes for brighter nights, but warmer days.

Over the years, the phases of the moon have been linked, often with dubious validity, to everything from the crime rate to hospital admissions. Now, two Arizona climatologists say they have solid evidence that phases of the moon really do affect global temperatures.

On average, the warmest day of every month occurs when the moon is full, the researchers reported Thursday. Averaged over many years, the coldest day occurs during the new moon, when the moon's dark side is facing the Earth. The difference appears to be due to the subtle warming effect on the Earth's atmosphere by the sunlight and heat reflected from the lunar surface.

"Averaged over the entire globe, the difference in temperature amounts to about two-hundredths of a degree," says Arizona State University climatologist Randall S. Cerveny. "That's not enough to make you decide to put on a jacket or change into short sleeves, but it's statistically significant." It's also about the same proportion of total incoming radiation that the Earth receives from reflected moon glow.

How did generations of sky gazers and prognosticators miss the effect all these years? Mr. Cerveny says the discovery, published in the current issue of the journal Science, was possible only because Earth-orbiting satellites have finally accumulated enough measurements to find such a small blip in the Earth's global temperature changes. Mr. Cerveny and his colleague, Robert C. Balling, used four different statistical methods to analyze more than 15 years' worth of satellite measurements.

"Folklore and myth have always contended that the moon has a powerful effect on us, and there's often a kernel of scientific truth in folklore," says Mr. Cerveny. "We've just managed to find that kernel."

Although the discovery will ultimately help scientists understand the multitude of factors that influence the Earth's climate, Mr. Cerveny says there's also another benefit.

"The next time someone looks up at the moon, they can know that it's more than just a pretty sight."

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