The science behind fall foliage

Published: Oct. 3, 2022 at 6:17 PM EDT
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GREENVILLE, S.C. (FOX Carolina) - One of the things we love about our area in the fall is the beautiful show Mother Nature puts on with the fall foliage. But if you’ve ever wondered why the leaves change color this time of year, here’s a break down of the science.

As we head into fall, the sun angle starts to drop in the sky. So instead of being directly overhead like it is during the summer, it sits lower in the southern sky. The days are also shorter leading to fewer minutes of sunlight and thereby cooler temperatures. Less sunlight and cooler temps both cause the chlorophyll, the substance in plants taht give them their green color in leaves to break down. As the green breaks down, the reds, violets, yellows and oranges emerge.

The color the leaves change is based off which chemicals are found in each type of tree’s leaves. Once the chlorophyll breaks down, the other chemicals have a chance to shine. When you see leaves turning yellow it’s thanks to xanthophyll. It’s the same photochemical found in papayas, peaches and squash. The burnt orange leaves emerge from leaves with carotene. Most often we hear carotene associated with carrots, which of course, are orange. And the deep reds and purples of the leaves is created by anthocyanin. This particular chemical is responsible for a variety of purple and red foods including cherries, blueberries and red cabbage. When the leaves have turned brown, it means the other chemicals have been used up and the only thing left is the tannins.

Chemistry of leaf color
Chemistry of leaf color(Fox Carolina)

The weather can have an impact on how vibrant the colors become. Dry weather and clear, chilly nights help the fall shades really pop. If there’s too much rain, it mutes the colors.

So we are in good shape this year for fabulous fall foliage with not a lot of rain recently and nice cool nights. In fact, we are already near peak around the North Carolina-Tennessee border in early October. By the middle of the month, the fall colors filter south and take over across the Southern Appalachians and even into northern parts of the Upstate. By the end of October, the foliage is peaking all across our area. So get out and enjoy the leaf peeping!

Fall foliage forecast
Fall foliage forecast(Fox Carolina)