Leafy Lab: The Science Behind Fall Colors

Image credit: Phil Ejercito

In the autumn, we see a beautiful change of color as the trees that are green in the summer become red, orange and yellow.  Due to the changes in sunlight and temperature experienced during the fall, trees undergo a chemical process that changes the color of the leaves.

During the summer, leaves have a very important job.  They are the factories where the food that trees need to grow is processed.  This happens in leaves containing a chemical called chlorophyll.  Chlorophyll absorbs energy from sunlight that is then used to convert carbon dioxide and water into carbohydrates.  Chlorophyll has a large amount of green pigment, giving leaves their color.  Other colors are present in leaves, but during the summer, the chlorophyll masks them.

In the fall, when it gets colder and there is less sunlight, leaves stop the food-making process.  Chlorophyll breaks down, and its green color disappears, allowing the other colors present in the leaves to become visible!

Read more about this incredible process here!

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