Once again autumn is upon us and with it comes the inevitable changing of the leaves. Each year the leaves turn from green to red, orange, yellow and—ultimately—brown during the most colorful season. In fact, to many people, the terms “fall” or “autumn” instantly evoke images of both Halloween and lots of colorful leaves falling to the ground.
Although everyone who lives in a location that experiences autumn the way that the Northeastern United States does is aware that leaves will change colors and then fall from the trees, fewer people understand the scientific explanation behind this occurrence.
Trees lose their leaves in the fall due to the breakdown of a chemical inside of them known as chlorophyll. Chlorophyll breaks down as a result of the changing weather conditions. When the temperature gets too cold leaves stop their food processes and this changes their chemicals which, ultimately, leads to the outwardly visual color changes.
A full explanation of why leaves change color can be found here: http://www.esf.edu/pubprog/brochure/leaves/leaves.htm
Not all trees lose their leaves in the winter. The pine tree—also known as an “evergreen”—is regaled for its pine leaves that never change color and remain on the tree all year long. Pine trees are most famous for being used as Christmas trees since they remain lush even in the coldest time of the year.
For more information about chlorophyll and why leaves chance color see this excellent online resource: http://www.chm.bris.ac.uk/motm/chlorophyll/chlorophyll_h.htm