(via) Fall officially arrives tomorrow. If you want to understand the chemistry behind the imminent turning of Vancouver’s leaves, study this handy chart by Compound Interest. Short version: “Leaves are green because of chlorophyll, yellow because of a combination of carotenoids and flavonoids, red because of carotenoids combined with anthocyanins, and orange when only carotenoids are present. The chart is presented with detailed explanations of each of the different pigments.” The more you know…