This week marks the 40th anniversary of Apollo 11 and the first landing of men on the moon. I recall, as if it were yesterday, feeling totally fascinated and enthralled while watching live, black-and-white TV pictures of Neil Armstrong and Buzz Aldrin taking mankind's first steps on the surface of the moon. The reality of it all, and everything it took to accomplish such a feat, seemed beyond belief. Only a few years earlier, landing humans on the moon seemed possible only through the imagination of sci-fi novelists and producers of low-tech sci-fi flicks.
At the time, I was a graduate student studying meteorology. Notwithstanding the amazing and breathtaking nature of the lunar landing, my weather-centric mind found me thinking, "What's the big deal? The moon has no atmosphere and therefore no weather." Of the multitude of concerns facing the moon-bound astronauts, weather conditions at their destination was not among them, seeing as the moon has no clouds, no wind, no lightning -- no weather at all.
The moon does, however, influence weather here on Earth. How so?
Keep reading to find out...
The gravitational influence of the moon is the primary driver of ocean tides, which can alter ocean currents and thus indirectly influence weather though air-sea interactions. For example, the transfer of heat and moisture to the atmosphere along the Gulf Stream -- the current of warm Atlantic Ocean waters off the East Coast -- can be critical in development of winter storms along the Eastern Seaboard. It's possible, though not well documented, that even a relatively small displacement of the Gulf Stream by tidal effects could on occasion alter the intensity and motion of a developing storm.
The moon also generates atmospheric tides. However, the impact of atmospheric tides on the lower atmosphere, or troposphere, where weather occurs is very small and likely overwhelmed by other atmospheric influences.
Aside from the revelations of modern science, alleged relationships between the moon and weather have been passed down from generation to generation throughout the history of mankind. Today they are enshrined in a collection of rule-of-thumb predictors that are part of weather folklore. While we now know that some of these sayings have a basis in science, this most certainly does not render them especially reliable. Nevertheless, here are some of my favorites. Feel free to add to the list in the comments section below...
A halo around the moon means rain or snow is coming soon.
(The larger the halo, the nearer the precipitation.)
Clear moon, frost soon.
Pale moon doth rain, Red moon doth blow, and White moon doth neither rain nor snow.
Waning Moon. Plant biennials, perennials, bulbs and root crops.
Waxing Moon. Plant annuals that produce their yield above ground.
If the tips of a crescent moon point upward -- bowl holding water -- expect a dry spell. If the tips point downward, expect rain or snow.
The number of days old the moon is at the first snow tells how many snows there will be that winter.
The heaviest rains fall following the New and the Full Moons.
And finally, this from Henry Wadsworth Longfellow's "Wreck of the Hesperus":
"For I fear a hurricane;
Last night the moon had a golden ring,
And tonight no moon we see."