Weatherz School: Why leaves change color
Every autumn, people come from far and wide to take in a view like this. But as you’re snapping your fall photos, have you ever wondered what causes the brilliant display of colors?
The green color in leaves comes from chlorophyll. In the summer, days are longer than nights, and all of that sunlight fuels chlorophyll production in the trees.
As the days become shorter, trees stop producing chlorophyll. Once that happens, the green fades, and other chemicals begin to show their colors.
Yellow pigment is from xanthophyll. Orange is carotene, and red is anthocyanin. The spectrum of colors that we see represents the spectrum of these chemicals in different types of trees.
The color change is driven by the change in daylight hours, but weather can play an important role in color change as well. Bright colors are most likely when late summer is dry and autumn has sunny days and cool nights.
Trees are very sensitive to their environment, so extreme weather changes like a drought or an early frost can cause leaves to fall off before they’ve changed colors. We saw that in the Northland last fall because of the drought.
This magic hour is closing, so be sure to take the fall colors in before they all end up on the ground.