Hola amigos: A VUELO DE UN QUIND EL BLOG., aquí en la imagen estamos apreciando el Hemisferio Norte con los grandes lagos de Norteamérica, captada por NASA’s Terra satellite , cuya imagen se en The Moderate Resolution Imaging Spectroradiometer (MODIS)
Fall Colors Arriving
A few days after autumn showed up on the calendar in the Northern Hemisphere,
it showed up on the landscape of North America. The Moderate Resolution Imaging
Spectroradiometer (MODIS) on NASA’s Terra satellite captured this view of fall
colors around the Great Lakes on Sept. 26, 2014.
The changing of leaf color in temperate forests involves several causes and
reactions, but the dominant factors are sunlight and heat. Since temperatures
tend to drop sooner and sunlight fades faster at higher latitudes, the
progression of fall color changes tends to move from north to south across North
America from mid-September through mid-November.
In late summer and autumn, tree and plant leaves produce less chlorophyll,
the green pigment that harvests sunlight for plants to convert water and carbon
dioxide into sugars. The subsidence of chlorophyll allows other chemical
compounds in the leaves—particularly carotenoids and flavonoids—to emerge from
the green shadow of summer. These compounds do not decay as fast as chlorophyll,
so they shine through in yellows, oranges, and reds as the green fades. Another
set of chemicals, anthocyanins, are associated with the storage of sugars and
give the leaves of some species deep purple and red hues.
Image Credit: Jeff Schmaltz at NASA GSFC. Caption by Mike
Carlowicz
NASA
Guillermo Gonzalo Sánchez Achutegui
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