Why do leaves change color?
PITTSBURGH (KDKA) -- We're really seeing trees changing to their fall colors around southwestern Pennsylvania.
We know the weather can have an effect on how brilliant fall foliage is from year to year. But why do leaves change color at all?
Are our eyes playing tricks on us? When we see green in leaves, that's just a mask. As we start prime leaf-peeping season this month, our favorite reds, russets and golds start to appear. But why and how do leaves go through this color change?
Leaves are green in spring and summer because they're filled with chlorophyll.
"Chlorophyll is kind of the rock star of the plant pigment world because it's the primary producer of photosynthesis," said Dr. Maria Wheeler-Dubas, the science education outreach manager at Phipps Conservatory.
Photosynthesis is the chemical reaction trees use to turn sunlight into sugars for food.
As weather cools and the days grow shorter, trees' chlorophyll breaks down leaving other chemicals that cause color change. That unmasks xanthophyll to produce yellows, carotenes creating oranges and anthocyanins giving us reds.
The weather affects those colors, making them brighter when late summer is dry and autumn has sunny days and cool nights. But why do trees go through all of this?
"They want to get rid of those leaves so that way they don't have to worry about repairing those leaves because if they freeze then you have tissue damage. And then you have to spend energy to repair the tissue damage," Wheeler-Dubas said.
While leaves are still green, you can reveal their hidden colors with a fun experiment at home that leaves behind bands of color pigments, including the green but also some of the leaf's true hues. You can read more about it here.
"We're already seeing a lot of colors in different places. Peak for our area is supposed to be second week or third week of October. So that's when we can expect to see the most colors. But you know, whatever you can do just get out and enjoy nature. Enjoy fall's spectacular display. It's wonderful," Wheeler-Dubas said.
