Fall foliage: when and why leaves change color in the fall

The science and timeline behind the arrival of autumn colors across the Brazos Valley.
Published: Sep. 24, 2020 at 7:50 PM CDT
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BRYAN, Texas (KBTX) - After Tuesday marked the first official day of fall in the Northern Hemisphere, many are gearing up for football season or heading out to grab a pumpkin spice latte. Over the next few months, morning and afternoon drives will eventually be accompanied by visions of oranges, reds and yellows as the leaves signal the arrival of fall.

For the Brazos Valley, it will still take some time for the leaves to completely undergo the color-changing process. Historical data from the National Oceanic and Atmospheric Administration suggests minimal changes in leaf color will arrive by mid-October. The leaves will then continue the changing process, with partial fall color transition by early November and peak fall foliage coverage by late November.

An estimated timeline of when the leaves will change colors across the Brazos Valley.
An estimated timeline of when the leaves will change colors across the Brazos Valley.((KBTX)(NOAA)(

The color-changing process that leaves undergo each autumn is the result of various chemical processes that take place throughout the changing seasons.

The majority of the process is related to the amount of chlorophyll in the leaf itself. The presence of this chemical is what gives the leaf its green color. During the spring and summer seasons, chlorophyll takes in energy from the sun and uses it to help the plant make food. While the leaf takes in the green pigment associated with the chemical, yellow and orange pigments are also included, but often masked by the greater amounts of green coloring.

Throughout the fall season, the days get shorter and the amount of daylight decreases which slows down the food-making process. The chlorophyll then breaks down and the green color dissolves, allowing the orange and yellow pigments to then become visible.

The type of tree can also play a role in exactly what colors the leaves portray, with sugar maples often depicting orange colors and oak trees displaying an assortment of browns.

Regardless of the exact shade, the fall foliage signals a season filled with football, trips to the pumpkin patch and the perfect mug of hot chocolate to be enjoyed with friends and family.

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