Why Leaves Change Colors

There are three major factors that influence the emergence of the colorful Autumn palette. The first and most important one is the length of the night. Fall is the time of the year when the nights become longer and colder. The shorter days and lessening intensity of the sunlight trigger the beginning of biochemical processes in the leaves.

Most of the year the leaves are green because of the chlorophyll in them. Chlorophyll absorbs energy from the sun for photosynthesis. The leaves then convert that energy into sugars and the sugars are then used to feed the trees. When Fall moves in, the temperatures drop, the days become shorter, and there is less intense sunlight. This all causes the chlorophyll to begin to break down. Once the chlorophyll breaks down it is destroyed and the color pigments that were actually already in the leaves but covered up by the green start to appear once the green is on its way out.

These leaf pigments, known as carotenoids and anthocyanin, are the second major factor in the leaves turning color. Chlorophyll is the other leaf pigment that we have already mentioned and that is what gives leaves the basic green color in the spring and summer. Once the green chlorophyll moves out the other beautiful leaf pigments are revealed. This is when we see the yellow, orange, red and brown colors come to life.

Weather is the last factor to influence the change of the colors. Warm, sunny days and cool and crisp nights seem to produce the most brilliant color displays. A Fall with less rain will contribute to vibrant colors. Too much rain and cloudy skies would dampen the colors. Year to year the amount of sun and rain vary, making every Autumn season unique and different from the one before.