LEAF PEEPING
Temperature Decreases with Altitude
If you’ve ever taken a hike on a crisp, fall day, you know firsthand that air
temperatures can start off mild at the base of the mountain yet quickly
turn cooler as you climb the summit. In fact, an increase in elevation of
just 1000 feet can equate to a temperature decrease of roughly 5.4 °F on
a clear day (3.3 °F if it’s cloudy, raining, or snowing). In meteorology, this
relationship between elevation and temperature is known as a lapse rate.
Certain broadleaf trees are noted and can be uniquely identified, by their
brilliant fall leaf color. In some cases, a tree’s common name is derived
from its primary autumn leaf color (red maple and yellow poplar). The most
common leaf colors of fall are red, yellow and ora nge and some species can
express several of these colors simultaneously as the season progresses.
How Leaf Color Develops
All leaves start out the summer as green.
This is because of the presence of a group of green pigments known as
chlorophyll. When these green pigments are abundant in the leaf’s cells
during the growing season, they mask out the color of any other pigments
that may be present in the leaf.
But with autumn comes a destruction of chlorophyll. This demise of green
pigments allows other masked colors to be expressed. Those unmasked fall
colors quickly become markers for individual deciduous tree species.
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FALL 2017 | VACATIONmode