Hello @leylar During the Spring and Summer Leaves act like a factory making the food necessary for the growth and survival of the tree chlorophyll is the main player in that process and chlorophyll makes the leaf look green. In fact, they're so much chlorophyll that hides the other colors present inside the leaf are other pigments that look yellow and orange a couple of things need to happen for these colors to be revealed. The first is day length in the fall short. Her days trigger the tree to stop making food leave are sealed off from the branches and any extra sugars are left behind next you need a few cooler evenings this confirms to the tree that winter is coming and it's time to protect itself and go dormant. So it continues to seal off the leaves. It also helps turn those sugars Left Behind red and purple. Finally. You need sunshine studies guys to burn off the chlorophyll faster than cloudy ones. As it disappears the brilliant yellows oranges Reds and purples are revealed and we see our fall colors.