File:Fall colors in eastern United States and Canada (15225458169).jpg

As temperatures dropped and daylight began to shorten, autumn colors began to wash over the deciduous forests of North America. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image of the northeastern United States and Canada on September 27, 2014.

Washes of orange, brown and yellow are brightest in the Upper Peninsula of Michigan, upstate New York, New Hampshire, Vermont, Maine, and southern Quebec and Ontario. Also, faint traces of phytoplankton blooms can be seen in the offshore waters of the Atlantic Ocean. The transition of autumn leaves from green, to glowing with colors, to browning and dropping to the ground, involve several complex interactions and reactions.

However, length of sunlight and the temperature changes are dominant factors. Topography also plays a role, as does latitude. Temperature tends to drop faster at higher elevations and at higher latitudes, and day length shortens more quickly at higher latitudes. Color change tends to begin in the north and sweep southward, and change begins at mountain tops then moves into valleys.

As explained by the U.S. Forest Service, certain species of trees produce certain colors. Oaks generally turn red, brown, or russet; hickories become golden bronze; aspen and yellow-poplar turn golden. Maples differ by species. Red maple turns brilliant scarlet; sugar maple, orange-red; and black maple, yellow. Leaves of some trees, such as elms, simply become brown.

Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team

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