A crisp Tuesday morning with bright sunshine is the perfect recipe for colorful leaves.

UMD’s NRRI’s Research Group Manager for Materials and Bioeconomy is Eric Singsaas. He shared some insight on those leaves so many people love to look at.

“The colors are generated by the tree in response to stressful conditions. One of the conditions is bright sunlight. The other is cooler temperatures,” Singsaas explained.

When it’s colder, a surplus of energy built up in the leaves can damage them. The red pigment provides a sunscreen-like shield. And the yellow pigment acts like a circuit breaker, Singsaas added.

Most trees have both kinds of pigments. But some, like aspen and birch, just have the yellow.

It keeps the leaves healthy as long as possible. Leaves are necessary to keep the tree itself healthy, to help absorb nutrients.

The real indicator for the fall color display is the more recent weather pattern, which hasn’t had cold, clear days. That’s why the colors haven’t popped in very many places yet, according to Singsaas.

Also, if your tree is east-facing, it’s likely those leaves will turn first.