The changing natural world at our doorsteps | Illustration and text by Patterson Clark
October 11, 2011
Foliage map: Autumn’s showy march to the sea
Although our nights are getting longer, Washington's trees are still mostly green. People who want to see fall color must drive north or into the mountains. The cooler temperatures there have triggered deciduous trees to stop replacing chlorophyll in their leaves. When the chlorophyll breaks down, weaker yellow pigments become visible. Red pigments are produced in some tree leaves, setting visual fire to the forest.
Peak dates for fall color are determined by a combination of latitude, elevation, the cooling effects of rainfall and proximity to the ocean.