The variety of colors of trees in autumn is related to photosynthesis , that is, the process by which the chlorophyll in the leaves converts water and carbon dioxide into food. In summer, green plants make large doses of chlorophyll. But when winter comes and the days get shorter, the production of this green substance is reduced. And we start to see other pigments. Carotenoids , for example, needed to capture sunlight, give leaves a yellow, sometimes deep gold color. Anthocyanin , present only in trees such as scarlet oak or some maples, generates shades ranging from red to purple.
The colors of this season are more intense when the autumn days are sunny and the nights are cold but the temperature does not drop below zero degrees. If this does not happen, the leaves die and turn brown.
