The Science Behind the Colorful Transformation of Leaves in Autumn
End of summer…or is it?
The end of summer typically happens with the Autumnal Equinox somewhere between September 21st and September 24th of each year. No, summer does not end on Labor Day each year, (and in NJ, after Labor Day, it’s called a Jersey Summer), but meteorologically, the experts say summer ends sometime the second half of August. That’s because the angle of the sun starts to change and head to a lower angle as we approach winter. Yes, I know it’s confusing, but hey, that’s Science!
Why is it important to understand the science behind the sun angle vs. cooler temperatures?
Each season, the angle of the sun as well as its proximity to Earth is what controls our seasons. Did you know that the sun is actually closer to us in winter than in summer? Hard to believe, but it’s true. So, why is it cold in winter and hot in summer? It’s all about the ANGLE! The higher the angle, the hotter it gets. Can you imagine what it would be like if in Summer, the angle was high AND the sun was as close as it can get? We’d heat up so badly that life on this planet may not exist as it does. Scary stuff, but we need not worry about something that doesn’t exist.
So, the angle matters to seasonal change and leaf color?
Yes indeed, the angle of the sun matters, but so do the cooler temperatures. As the angle lowers approaching winter and the hours of sunlight lessen, trees and shrubs start to “shut down.” What does that mean? All spring and summer, water and nutrients move up into the canopy(leaves) of the plant and help it survive a long half year. Once fall approaches, the focus of the plant material is to get the moisture and nutrients back to the root system. When they do that, the petioles, or stems seal off, cutting off all materials from getting to the leaf system.
No water, no nutrients…so what?
With water and nutrients being essentially “cut off” from the leaf system, the leaves begin to die and then eventually “fall” off, but before that happens, most deciduous trees turn unbelievably vivid colors of red, yellow, orange and russet, with a little purple too. And that’s where the cooler temperatures come in. It’s the cooler temps that cause the color change. With water lacking in the leaves, the sugars concentrate causing the leaves to turn these beautiful colors I mentioned earlier. Photosynthesis stops for the season and the colors of Autumn come through for weeks of natural enjoyment, so get out there and enjoy the natural wonder of fall. In my opinion, there’s nothing as wonderous and simple as this.
What trees are the best for fall color?
There are so many deciduous trees that turn wonderful colors in fall, and of course, it depends on where you live. Here in New Jersey, some of the best choices for fall color are:
Enjoy fall in New Jersey or wherever you may live… there’s nothing like it!