Why do leaves change colors?
1. Every spring, leaves are born containing green, red, orange and yellow pigments. Yet throughout the spring and summer, green is the dominant color due to chlorophyll production. (Chlorophyll is created by sunlight during the process of photosynthesis.) So the other pigments are drowned out.
2. Come fall, a number of factors come together to influence autumn coloration in the leaves. The most important is day length, followed by rainfall, the amount of sugar in the leaves, the wind, and the weather; particularly if there is sunny autumn weather without a killing frost. The brighter the light during this period, the greater the production of pigments. These variables are why some autumns you'll get brilliant coloration, whereas other years the leaves are duller.
3. The brightest and most colorful autumns occur when the days are sunny and cool, while the nights are chilly but not freezing. The production of chlorophyll slows down during this time.
4. As days grow shorter and the hours of sunlight decrease, the green pigment recedes and starts to disappear, allowing the other underlying colors to start to show. These can include red, orange, yellow, even scarlet or purple. As the tree senses the change in the weather and prepares for the winter, it emits a waxy substance where the leaf meets the branch. Not only does this protect the tree from the weather, but it loosens the leaf and allows it to separate from the branch. This is why the same leaves that can withstand strong rainstorms and fierce wind during the summer falloff so easily at autumn.
So now you can teach your kids why leaves change colors!