WASHINGTON (DC News Now) -- Now that fall is in the DMV, leaves will continue to change across the area. But what is the science behind the leaves changing? Leaves have three main ingredients: sunlight, carbon dioxide, and water. Leaves have something called chlorophyll. Chlorophyll is the green pigment in the leaves that helps trap sunlight that provides plants/trees food during the growing season. Police identify 16-year-old boy killed in Southeast DC shooting During the summer months, the sun is at its highest peak in the school. However, when seasons change from summer to fall the sun angle begins lower. As the angle is lower, the sun is not as intense as it would be during the summer. Because the sun angle is lower and less intense, the cells form at the base of the leaf and stop carrying fluid. And we will slowly start to see the leaves change color.