Fall colors set to peak for Oct. 17
COLUMBIA - An upcoming frontal system later this week accompanied with cool air, clouds and rain may be the likely cause for rapid color change of tree leaves this upcoming weekend. Look for near-peak color conditions near Oct. 17 and post-peak conditions around Halloween.
Tree leaves are not naturally green. The green appearance is due to chlorophyll within the leaves absorbing the red and yellow light from the sun, but reflecting the green light. Other pigments such as red, orange and yellow exist within the leaf, but are hidden by the chlorophyll.
Chlorophyll is broken down by sunlight in a process called photosynthesis and feeds the plant.
As days get shorter, the lesser amount of daylight leads to a slowing in production of chlorophyll within the leaf. This leaves behind the other compounds in the leaf, such as carotene which is naturally orange.
Different species of trees will provide different colors. Oak leaves turn a reddish brown. Maple leaves can many colors, ranging from deep, vibrant red to orange and even yellow. Dogwood trees that scatter the Show-Me-State have a purplish red leaf. Other hardwoods such as poplar have yellow leaves.
Although the spring and early summer were dry, heavy rains in July and near average summer temperatures helped rebound soil moisture levels, reducing stress on the trees. A few weeks of warm, dry weather since mid-September has delayed the onset of leaf color change. However, sunny afternoons with cool evenings have allowed for sugars to build up in the leaves, adding to their natural color.