The Science Behind the Fall’s Colorful Foliage

The colors of autumn.Photo: paul (dex)

Marked by stunning red, orange and yellow hues, the colors of Autumn never cease to attract and delight those with a fondness for nature’s unrivaled artistry. But what is the science behind this annual explosion of color?

Mountains and Fall ColorsPhoto: mellowrapp

The phenomenon is not, as many believe, the result of cooler temperatures or the presence of early frost. The key to these colorful displays is actually linked to the Sun’s impact on plants’ botanical processes and the decrease in sunlight caused by the tilt of the Earth’s axis.

A deciduous tree maintains its rich green color throughout the Spring and Summer by constantly supplying the leaves with chlorophyll, which is naturally degraded by Sun exposure. When the region in which a tree is situated moves away from the Sun — the changing of the season — the amount of sunlight begins to decrease, as does the tree’s chlorophyll production.

Autumn lakePhoto: LiamDC

This absence of chlorophyll allows other pigments present in the leaves to show through, including anthocyanins (responsible for red, blue and violet hues), tannins (brown), and carotenoids and carotenes (orange and yellow). In effect, the leaves are actually losing their dominant color, green, while gaining the vibrant tones and tinges that so beautifully accentuate the harvest season.

Autumn leavesPhoto: sigusr0

Sources: 1, 2