Autumn is one of four seasons that occurs from roughly September 21 through December 21. It is more commonly known as "fall" because the leaves fall off of deciduous trees during the season. Here are some interesting facts about autumn leaves:
- Leaves require sunlight, water, chlorophyll and carbon dioxide to make food for themselves. As winter approaches, leaves create a coating for themselves that blocks their water source... in the absence of water, the leaves no longer produce chlorophyll (chlorophyll is what makes leaves green).
- When the leaves turn colors in the fall, they actually are returning to their normal colors. During the summer months, the chlorophyll present in the leaves causes the leaves to turn green, blocking the their actual colors.
- Along with chlorophyll, there are two other chemicals that cause the coloring in leaves. The first is called xanthophyll, which is yellow in color. The other is carotene, which is orange in color.
- Red and purple leaves are actually caused by the presence of sugars from sap that is trapped inside of the leaves.
Once the leaves have turned brown, they are dead and no longer receive any nutrients. When spring arrives and new leaves appear the cycle begins again and we witness the beautiful colors once again.