HUNTSVILLE, Ala. — During the spring and summer leaves have served as factories where most of the food necessary for the tree's growth is manufactured.
This food-making process takes place in the leaf in numerous cells containing chlorophyll
Chlorophyll is simply a green pigment. It appears green thanks to it’s ability to trap sunlight
As the season transitions from Summer to Fall the sun angle lowers therefor the intensity of sunlight decreases
As sunlight decreases, cells form at the base of the leaf which keeps the food made in the cells from being transported throughout the tree.
When this happens the chlorophyll production is stopped and broken down into other smaller molecules and sugars. The green pigment is no longer dominant and other colors shine through before the leaves fall off the tree.