We’ve all heard this before: “If you don’t ask, you won’t know.”
I live by it, so I love when people send in questions. A few weeks ago, Audrey Barlow from Warren Grove, P.E.I., wrote in and was curious about something her dad used to say about the leaves on the trees. I thought I should get to it now before all the leaves are down!
Audrey remembers her dad saying, “It’s going to rain by the look of the leaves on the silver maple.”
Audrey, Grandma said the same thing!
She could tell if she should hang laundry out to dry by the way the leaves looked. Grandma would say “when the leaves are backwards on the trees – rain was on the way.”
As a child, I found the notion of the leaves being backwards on the trees quite perplexing. I came to learn that what Grandma meant to say was if you could see the underside of the leaves, there was rain coming. Not surprising was the fact that this too can be explained scientifically.
Atmospheric conditions are responsible, mainly wind. Across North America, our prevailing winds are westerly; in the winter, they become a little more north-westerly and, in the summer, a little more south-westerly. That being said, as the leaves grow on the trees they are held down by the prevailing westerly wind. When a rain storm approaches, counter-clockwise winds around its centre produce an east wind. That wind goes against the flow. So the east wind will pick up the leaf and flip it over. As the sky darkens, the undersides of leaves become more visible and the mosaic patterns of lighter green mixed with darker green become more enhanced. By observing these leaf patterns, along with a darkening sky and wind, you can predict rain is on the way in the immediate future.
Thanks for asking Audrey.
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Cindy Day is the chief meteorologist for SaltWire Network.