What Makes The Leaves Turn So Vivid Each Year?

What's behind the beguiling colors of autumn?
If you're lucky enough to live in a part of the country where there are four distinct seasons you know that this time of year can be dazzling. 
And hopefully, you're wise enough to take the time to enjoy the vivid hues of the season.
We've been doing just that. We've slowed down, looked up, and savored arborland's big, bright show. The above photos are the result. All of these photos were taken within the past few days in the Philadelphia region.
It's been my experience that when it comes to autumn, nature is much more reliable than Broadway or Hollywood. This show's always a winner. There are no flops.
The changing of the leaf colors is the way that trees begin to prepare for winter.
A process called photosynthesis helps keep the leaves green through spring and summer. A chemical called chlorophyll helps make photosynthesis happen. Chlorophyll is what gives plants their green color.
As the days get shorter and there is less and less sunlight, the trees realize that winter is coming. They cannot support their leaves. During winter there is not enough light and water to sustain the leaves. The trees will rest and live off the food they stored during the summer. 
Animals grow a furrier coat to prepare for winter. Trees shed their leaves.
As the trees begin to shut down their food-making factories, the green chlorophyll disappears from their leaves. The bright green fades away and we begin to see yellow and orange colors. Small amounts of these colors have been in the leaves all along. We just can't see them in the summer, because they are covered up by the green chlorophyll.
That's science's explanation. 
However you explain it, the result is a time-honored show.
Get out and enjoy the razzle-dazzle before the curtain comes down on this magical spectacle. It's fantastic!

Besides the autumn poets sing,
A few prosaic days
A little this side of the snow
And that side of the haze.
~Emily Dickinson

No spring nor summer beauty hath such grace
As I have seen in one autumnal face.
~John Donne 

Autumn is a second spring when every leaf is a flower.  
~Albert Camus