Why do leaves change colour in the fall? Ashley Brauweiler has the answer


Ahhh, fall.

The crisp, cool air. Thick, cozy sweaters. Pumpkin-spiced everything. And of course, the magnificent, vivid colours of changing leaves.

But have you ever wondered why leaves change colour before falling from their trees? CBC Meteorologist Ashley Brauweiler has the answer. 

"The red, orange and yellow leaves actually have these colours in them all year round — and that's thanks to chemical compounds," she said. 

To understand why leaves change colour, first you need to know why they're green most of the year. 

Watch: CBC N.L. Meteorologist Ashley Brauweiler explains why leaves change colour

The answer: chlorophyll.

It's a green pigment key to photosynthesis, the process by which plants turn carbon dioxide and water into sugar.

"Chlorophyll requires sunshine and warm days, so when we start to lose the sun and the heat, the chlorophyll starts to die off revealing the natural colours of the leaves."

Turns out, weather has an impact on leaf colour, too.

"Low temperatures, rain and overcast days are actually the best for bright colours," Brauweiler said. 

"But clear, dry days ... are the best for enjoying them."


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