A few weeks ago, we posted an explanation for the “Red Sky at Morning” adage, where it comes from, and why it’s so. But it got me thinking about another naturally occurring phenomenon (and a story about my grandfather).

Now, my granddad was the kind of guy who was always a bit leery of the weatherman. As far as he was concerned, the weather could be predicted simply by looking at the leaves on the trees.

“When the leaves turn upside down, a storm is on the way.”

I never really knew where it came from, but I noticed that “upside-down leaves” is usually a pretty good indication of approaching rain. But a few days ago, I stumbled across a real scientific explanation:

On a normal, sunny day, fluid pressure in the branch, twig and leaf keep the upper surfaces of leaves facing the sunlight. But when the tree “senses” a change in ionization (or clash of warm and cool air that typically signals the approach of a storm), it reduces that pressure. When that happens, the leaf turns over and shows its silvery underside. It’s all a way for the tree to protect its branches from rain and high winds.


They say that animals can sense bad weather…but a tree? Wow.

I guess it proves that trees are smarter than we ever realized. And come to think of it, so was Granddad.