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There are many things that come to mind when we think about Autumn. Things like pumpkins, apples, a new school year, and Halloween all play a major part in the autumn feeling. And many of us live in areas that help define what autumn is all about, because the leaves on the trees change all different kinds of colors. This changing of colors is called foliage. But did you ever wonder what makes the leaves turn to vibrant reds and oranges and yellows? Let’s take a look and find out.

During the course of a year, leaves and trees are exposed to certain amounts of sunlight. In the spring and summer months, leaves receive much more sunlight than in the autumn and winter months. All plants need sunlight for energy and nutrients. And in each leaf, a substance called chlorophyll absorbs this sunlight to make sugar and carbohydrates, which act as food for the plant. This process is called photosynthesis. As the days become shorter at the beginning of fall, and the amount of sunlight decreases, so does photosynthesis. What this means is that the leaves are getting less and less nutrients. But, these leaves are smart, because as the sunlight decreases, the base of the leaf forms a hard layer to cut off the nutrients. The leaf knows that there won’t be enough sunlight for it to produce food, and by blocking the nutrients, it allows them to flow straight into the tree. That’s pretty nice of them, don’t you think?

Ok, but this still hasn’t answered the question of why leaves change color. Well, remember that stuff called chlorophyll that helps make food for the plant? Chlorophyll is full of green, so as it starts to break down with the decrease in sunlight, the green begins to fade. This is when the yellow starts to show its true color. In fact, the yellow had been there all along, but because of the large amounts of chlorophyll in the spring and summer, you don’t see it. And as for those beautiful reds, oranges and violets, they are caused when the sugars become trapped in the leaves.

Don’t forget that weather has a role in this process too. The more sunlight and rain in the summer and sunny days and cool nights in the fall give the leaves the most vibrant of colors. The foliage in the Northeast of the U.S. is the best place to see foliage because this region has the largest variety of trees that lose their leaves each year and the changes in temperature climate are needed for the bright colors.