Why Do Leaves Change Color in Autumn???

Each autumn, eastern Kentucky looks as if an artist has taken his paintbrush and created a mosaic of beautiful, vibrant colors as the leaves change from green to various shades of red, orange and yellow. Have you ever wondered what makes this change occur?
Leaves changing colors in autumn is a process that trees undertake to get ready for the winter. The change in the color of the leaves has to do with the pigmentation within the leaves. All during the spring and summer months, the leaves serve as factories where most of the foods necessary for the tree’s growth are created. The process of making this food actually takes place inside each leaf in the cells that contain chlorophyll. Chlorophyll actually masks the true color of the leaves by absorbing all other light colors and reflecting only the green light spectrum, thus making the leaves appear to be green.
When the days become shorter and the temperatures become cooler at night, several changes start to take place inside the trees. One major change is the development of a corky membrane between the branch and the leaf stem. This membrane interrupts the flow of nutrients into the leaf, thus slowing down the development of chlorophyll in the leaf. As the Chlorophyll decreases inside the leaf, the green coloration begins to fade.
The different chemical components that are present inside each leaf determine whether it will be red, orange or yellow. Weather plays a factor in determining the color of the leaf. Leaves that are exposed to the sun may turn red, while those that are shaded may be yellow or orange. The intensity of colors on the same tree may vary from year to year, depending upon the combination of weather conditions. According to the tree experts at several universities, the most vivid colors appear after a warm, dry summer combined with early autumn rains. Long periods of wet weather in late fall will produce a rather drab display of colors. The bright reds and purples are made mostly in the fall. The brown color of trees like oaks is made from wastes left in the leaves.
Temperatures also play an important role in the coloration of leaves. The best colors seem to be visible when warm and sunny days are followed by cold nights through early October. Light frost will enhance the colors, but a hard, killing frost will cause the leaves to drop off the trees at a quicker pace.