- During the fall, in some parts of the world, leaves on deciduous trees will change colors.
- There are three things that can tell a tree it is time to change colors: weather, types of leaf pigments and how long the nights are. Shorter nights are the most important factor of the three. Since longer nights are cooler and reduce the amount of sunshine in the day, this triggers the tree to start its color changing transformation.
- The color changing process incorporates three different types of pigments. Chlorophyll is used to create food for the tree and is what gives leaves their nice green color. Also in the leaves are carotenoids and anthocyanins. These two pigments are found deep within the leaves.
- As the nights become shorter and colder, the tree stops making chlorophyll. Without the chlorophyll, the carotenoids and anthocyanins show up more clearly. Carotenoids are responsible for the brown, orange, yellow and gold colors, while anthocyanins are responsible for the red tones.
- Sometimes this process can be interrupted or started sooner than normal. A drought can cause leaves to skip the color changing process and turn brown. A sudden cold snap can make the leaves change color more quickly.
- Slow and steady changes are what make trees change color the best. Areas that have gradual changes in temperatures and stay cold without freezing tend to have better displays of color than others.
