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Why do leaves change color? A look at the science behind fall colors and when they will peak in Denver


DENVER (KDVR) — Every fall as the temperatures drop and the days become shorter, colorful leaves put on a show in Colorado.

During the warmer months with more sunlight, leaves are green because they are producing chlorophyll through photosynthesis. The process of photosynthesis helps to keep leaves strong and healthy.

Chlorophyll is the pigment produced during this process that gives leaves its green color.

When temperatures drop in the fall and there is less sunlight the leaves do not produce as much chlorophyll. As the green color starts to fade, other colors become more visible in the leaves.

There are three pigments that produce fall colors in leaves: xanthophyll, carotene, and anthocyanin. Xanthophyll produces a yellow color, carotene produces orange, and anthocyanin gives leaves a red color.

Weather extremes like drought and big temperatures swings can put stress on leaves causing them to fall off before the color has a chance to change. The brightest colors are typically produced from dry weather with cool nights in the fall.

Most of Colorado’s mountains are either at or past their peak colors. Colors are expected to peak on the Front Range in the next week or two.

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