|Entertaining TV for nerds and people who like explosions.|
One of the primary reasons I bother with learning the science of things though is so that I might later be able to tell someone that they are wrong. Petty, I know.
While following links today, I was led to the web site of a professor of plant physiology at Appalachian State University. He calls himself “The Fall Color Guy.” That sounded like a good place for scientific simpleton's like me to find a few takeaway factoids that could prove useful to me later on.
My step father is of the age where he has a few pet shticks. One of them is a conspiracy theory related to Daylight Savings Time. Another one is that he has always claimed that leaves change colors in the fall because of the changing trajectory of the sun’s light waves. That’s the kind of thing that sounds just scientific enough that it could be true but it also sounds like total bull to me because I am pretty sure it has something to do with chlorophyll and not light. But I never challenged him on it because I didn't know the real, complete answer. I have operated on the assumption that it had something to do with the colder temperatures causing chlorophyll to recede from leaves but I had no idea if that was totally correct and I had no explanation for why the colder weather would cause that effect.
|This is what passes for fall "color" in my neighborhood.|
So, having stumbled upon a site written by the Fall Color Guy, I decided it was high time I got an actual, reliable scientific explanation for what causes the color of leaves to change in the fall even if it meant I would have to turn on, warm up, and then actually use the left side of my brain to decipher the explanation.
I clicked around the web site trying to find a one-sentence answer along the lines of “because it gets cold and trees stop making chlorophyll in the cold” when I stumbled upon the following paragraph:
“Why do leaves appear Green? [emphasis added] The green color in leaves results from the production of a compound called chlorophyll (chl). We see the leaf as green because this compound is most efficient in absorbing red and blue wavelengths of light, and relatively inefficient in absorbing the green wavelengths. This means that the light reflected from the leaf back to our eyes is enriched in the green spectrum, making it appear green to us.”
I’ve been thinking about this for a couple hours now. It is, quite frankly, blowing my mind. This isn’t just science we're talking about, its philosophy. Its metaphysics!
|Aristotle - the "father of metaphysics". I wish I could ask him about how we know what colors we are really seeing.|
Given that he has apparently lost all his color, I think he'd have something important to say about the subject.
If the leaf just appears to be green then that statement implies that the leaf isn't really green. And if it isn't really green then couldn't it be said that green leaves don’t really change colors in the fall since they weren't green in the first place? Do leaves merely appear to change colors in the fall? Or, more accurately, do we just start seeing leaves as they really are when fall comes? If that’s the case, then what sounded like an absurd supposition made by my step father could actually have some truth to it. After all, if the chlorophyll does a bad job at absorbing green wavelengths, could the different trajectory of light waves in the autumn reduce the amount of green wavelengths reflecting off leaves?
Clearly, I still had too many questions to let it rest at this so more reading was required.
|A Japanese maple photographed in November of 2010 with what "appears" to be fall colors.|
A few clicked links later and I was on the USDA Forest Service's web site which had a page titled "Why Leaves Change Color." It still didn't provide me with a sound byte answer, but this was close:
"During the growing season, chlorophyll is continually being produced and broken down and leaves appear green. [There's that word "appear" again!] As night length increases in the autumn, chlorophyll production slows down and then stops and eventually all the chlorophyll is destroyed. The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors."Okay, I accept that it's a scientific process that causes leaves to appear to change colors in the autumn. But I prefer my philosophical interpretation of the annual occurrence: leaves only reveal their true identities in the fall. In my half-working mind, the changing colors of leaves encourages me to remember that what I see on the surface isn't always a true reflection of the essence of a thing. I suppose that's true for people too.
The USDA's web site had some other good explanations for what triggers the changes in color, what leaf fall does to the tree, and what role weather plays in it all, but frankly, I OD'd on science for today and I'll just have to bookmark the site for future reference. Hopefully I'll get back around to it before my mom and her husband come to visit again.