What Makes Leaves Change Color Every Fall?

The reds and oranges of fall leaves show up when there's less sunlight to take advantage of.
SMS
What Makes Leaves Change Color Every Fall?

You know it's fall when the leaves start to turn. But what causes this riot of color?

Deciduous leaves have four pigments year-round: green, yellow, orange and red.

Most of the time, they're green. The color comes from chlorophyll, which the trees use to photosynthesize. 

SEE MORE: Right Before Cold And Flu Season, And Florida's Oranges Are Dying

In fall, days are shorter. With less sunlight, chlorophyll becomes less important, and the leaves make less of it. The other colors get their chance to show.

When it happens depends on how cold it gets. Trees will change their colors in cooler weather. When it gets really cold, the leaves just fall off.

Featured Stories
A municipal power plant in California.

The US Will Battle Climate Change Without Washington's Help

Treasury Secretary Steve Mnuchin

Trump's Treasury Secretary Might Have 'Jokingly' Broken Ethics Rules

Scottish First Minister Nicola Sturgeon

Scottish Parliament Supports Independence Referendum Ahead Of Brexit