Has the Show Begun?
The question is asked with the same anticipation you hear in a child’s voice before the holidays. My friends from afar email to ask about the yearly display of fall colors. And while the obvious answer looking out my window at a yellow birch in full verdant foliage is that the show has not quite started yet, the more truthful answer is that prelude has already begun.
As related in the most recent blog entry, during the summer most leaves appear green due to the green pigment chlorophyll. With shorter days and cooler temperatures the plants stop producing chlorophyll and process of senescence becomes apparent through color change. As the green chlorophyll breaks down and is no longer replaced, other pigments already in the leaves, begin to shine through.
We can just begin to see this happening in the forest as we look across at Mount Washington from Square Ledge in Pinkham Notch. Now in late August at 13:12 hours, we already experience 3 fewer hours of daylight than we did in mid June. Increased nighttime hours and the recent cool nighttime temperatures a week to 10 days ago triggered the halt in chlorophyll production. The landscape, lacking that rich vibrant shade of summer green, is slowly taking on a more yellowish tint. In the next week we should see more of the unmasking of yellow xanthophylls and orange carotenoids as more of green chlorophyll breaks down.
So the show really has begun. Changes are faint, but soon the shift will be overwhelming. Check out this site for weekly photos to as the drama unfolds.