Leaves change color in the fall because of the chemical processes that take place as the weather gets cooler and the days become shorter. During this time, chlorophyll production decreases in the leaves, which is the green pigment responsible for photosynthesis. This reduction in chlorophyll reveals other pigments such as carotenoids (yellows and oranges) and anthocyanins (reds and purples), giving the leaves their vibrant fall colors.
