Autumn has arrived, my favorite season for creative photography. To kick off the festivities, I’m sharing an updated version of a post I wrote a few years ago explaining the often misunderstood process responsible for it all.
Few things get a photographer’s heart racing more than the vivid yellows, oranges, and reds of autumn. And the excitement isn’t limited to photographers—to appreciate that reality, just try navigating the Smoky Mountains backroads on a Sunday afternoon in October.
But despite all the attention, the annual autumn extravaganza is fraught with mystery and misconception. Showing up at the spot that guy in your camera club told you was peaking at this time last year, you might find the very same trees displaying lime green mixed with just hints of yellow and orange, and hear the old guy behind the counter at the inn shake his head and tell you, “It hasn’t gotten cold enough yet—the color’s late this year.” Then, the next year, when you check into the same inn on the same weekend, you find just a handful of leaves clinging to exposed branches—this time as the old guy hands you the key he utters, “That freeze a few weeks ago got the color started early this year—you should have been here last week.”
While these explanations may sound reasonable, they’re not quite accurate. Because the why and when of fall color is complicated, observers resort to memory, anecdote, and lore to fill knowledge voids with partial truth and downright myth. Fortunately, science has given us a pretty good understanding of the fall color process.
It’s all about the sunlight
The leaves of deciduous trees contain a mix of green, yellow, and orange pigments. During the spring and summer growing season, the green chlorophyl pigment overpowers the orange and yellow pigments and the tree stays green. Even though this chlorophyl is quickly broken down by sunlight, it is continuously replaced in the process of photosynthesis that sustains the tree during the long days of summer.
As the days shrink toward autumn, things begin to change. Cells at the abscission layer at the base of the leaves’ stem (the knot where the leaf connects to the branch) start to thicken, blocking the transfer of carbohydrates from the leaves to the branches, and the movement of minerals to the leaves, that had kept the tree thriving all summer. Without these minerals, the leaves’ production of chlorophyl dwindles and finally stops, leaving just the yellow and orange pigments. Voila—color!
Sunlight and weather
Contrary to popular belief, the timing of the onset of this fall color chain reaction is much more daylight-dependent than temperature- and weather-dependent—triggered by a genetically programmed day/night-duration threshold, and contrary to innkeeper-logic, the trees in any given region will commence their transition from green to color at about the same time each year (when the day length drops to a certain point).
Nevertheless, though it doesn’t trigger the process, weather does play a significant part in the intensity, duration, and demise of the color season. Because sunlight breaks down the green chlorophyl, cloudy days after the suspension of chlorophyl creation will slow the coloring process. And while the yellow and orange pigments are present and pretty much just hanging out, waiting all summer for the chlorophyl to relinquish control of the tree’s color, the red and purple pigments are manufactured from sugar stored in the leaves—the more sugar, the more vivid the red. Ample moisture, warm days, and cool (but not freezing) nights after the chlorophyl replacement has stopped are most conducive to the creation and retention of the sugars that form the red and purple pigments.
On the other hand, freezing temperatures destroy the color pigments, bringing a premature end to the color display. Drought can stress trees so much that they drop their leaves before the color has a chance to manifest. And wind and rain can wreak havoc with the fall display—go to bed one night beneath a canopy of red and gold, wake the next morning to find the trees bare and the ground blanketed with color. And of course all these weather factors come in an infinite number of variations, which makes each year’s color timing and intensity a little different from the last.
Despite our understanding of the fall color process, Mother Nature still holds some secrets pretty close to her vest—just when we think we’ve got it all figured out, she’ll surprise us. For example, last year’s Eastern Sierra fall color featured lots of black leaves that I attributed to California’s extreme drought conditions. With the drought persisting, and in fact intensifying, this year, I feared this fall would be even worse. So I was quite pleased to find everything going along right on schedule, with lots of yellow, more red than usual, and hardly a black leaf to be seen. Go figure.
About this image
Driving Rock Creek Canyon north and east of Bishop, I pulled my car over at a random spot and wandered over to the creek. I found trees beyond peak and the creek bank blanketed with yellow aspen leaves, by far the predominant color in the Eastern Sierra. As I turned to return to my car my eyes caught a rare flash of orange. Moving in that direction, I found matching red-orange leaf less than a foot away.
I’m sometimes accused of placing or arranging leaves in my scenes, something I never do, but I understand why people might think that. I very consciously look for leaves that stand out from their surroundings that I can isolate in my frame.
Circling this scene, I didn’t have to work to hard to decide that a symmetrical diagonal arrangement was the way to go. A thin overcast made exposure easy.