The Moon and Weather
Every weather forecaster wishes he could do as well as did Lieutenant S. M. Saxby of the British Navy one day in November 1868. He predicted, nearly a year in advance, that on October 5, 1869, the northeastern United States would experience an exceptionally violent hurricane with abnormal tides. A friend predicted the landfall of this storm to be Halifax, Nova Scotia. Sure enough, within 12 hours of the designated time a hurricane of great violence did strike, and it landed within 100 miles of Halifax.
Lt. Saxby stated that his prediction was based upon the moon's position. He knew that on October 5, 1879, the moon would be at its closest approach to earth, and it also would be very nearly on the line joining the center of the earth to the sun--conditions that cause the moon and the sun to pull best in unison to create the highest tides. Thus, Saxby's prediction of abnormal tides on October 5 was firmly based on known facts.
About the basis for his prediction of a hurricane on that date, one cannot be so sure. But certainly if a strong hurricane did occur on that date of abnormal tide, it was bound to create unusual flooding damage.
Though scientists have generally been unable to find physical reasons to explain a lunar influence, weather prophets, down through the years, have relied heavily on the moon. In New England it was said that "the number of days old the moon is at the first snow tells how many snows there will be that winter." Ben Franklin in Poor Richard's Almanac based his weather predictions upon the lunar phase. He hedged his bets slightly by stating: "I should ask the indulgence of the reader for a day of grace on either side of the date for a specific weather prediction."
The ability to predict the weather is a definite asset for many reasons, social, scientific and economic. Consequently, searches are underway to detect relationships between weather and other phenomena, and hopefully to learn the mechanisms that create such relationships.
One recent study by the National Weather Service indicates that, in the country as a whole, about 10% more rain and occasions of heaviest rain occur in the days following new or full moon--that is, in the days following the greatest tidal variation each lunar month. Another study indicates the greater tendency for tropical storms to attain hurricane status at these same times.
Why these tendencies should exist is not known. The nature of the reported tendencies suggests the influence of tidal forces, but no one seems to know how they might act to affect the development of storms. If Lieutenant Saxby knew, the secret seems to have died with him.
