The colors of autumn are truly something to behold. The leaves change color every year, and we get to enjoy the beauty of the fall season before winter arrives. The beauty of fall makes it impossible to take the wonder of nature for granted. The subtle oranges and yellows conjure up images of bonfires, Halloween costumes, and cool evenings under the stars.
While most people love and appreciate the beauty of fall and its changing colors, they do not understand why this occurs. Fall is a very spiritual time for many; it serves as a balance between darkness (winter) and light (summer). It is also a reminder of the impermanence of life. The leaves change color and begin falling from the trees, eventually deteriorating into the soil below.
Despite the spirituality and poetry of the changing season, there is actually a relatively simple scientific explanation for leaves changing color in the fall. In order to better understand this yearly ritual of nature, let’s look at how leaves are composed and what causes them to change at the same time every year.
The Purpose of Leaves
In addition to being visually stunning throughout most of the year, leaves also serve an essential purpose for trees and other plants. Leaves produce much of the energy needed to sustain plant-life. They help keep plants healthy and ensure that they will continue growing throughout the spring and summer. The cells in leaves responsible for this process also contain chlorophyll, which is what gives leaves (and many other plant parts) their green hue.
That said, leaves also contain other pigments that produce different colors (like orange), but these colors are overpowered during the warmer months by chlorophyll. Since leaf cells are busy producing food, they are also busy producing more chlorophyll. However, in autumn, an interesting change occurs.
Why Leaves Change Color in the Fall
The long days of summer begin to equalize in the fall, and this change also causes temperatures to drop. When this occurs, leaves no longer receive the energy needed to produce food. As the food-making process slows to a standstill, chlorophyll also begins to breakdown, giving way to other pigments that are naturally present in leaves, namely red, orange, and yellow. There are also other chemical processes that cause certain tree leaves to show one color more than another.
While these chemical processes are taking place, cells grow closer to the stem, causing it to break free from the branches. This is what causes the cascade of beautiful leaves that crunch beneath our feet every autumn. As fall turns into winter, most trees have lost all of their leaves, though certain species of trees keep many of their dead leaves attached. In any case, winter causes the temperature to drop further, and the days to become even shorter. When this happens, the beautiful oranges and yellows and reds turn to brown, and the leaves eventually wither and are then reabsorbed into the soil.
So, while poets often write about the beauty of autumn and its many colors, the reason for these changes is just a matter of simple science!