Sun glint (right) and vegetation hot spot (left) in Zambia

A bright green streak runs through the vegetation of western Zambia’s Kafue National Park (image left), just north of Itzehi-Tezhi Dam. The streak is called a vegetation hotspot; the term implied that the reason for this distinct coloration is that this region’s vegetation is hotter than the surrounding vegetation. However, this is not the case. This hotspot is actually a light phenomenon; light from the Sun strikes the leaves on the vegetation at such an angle that light bounces off of them and directly into MODIS’ “eye,” which creates the streak of lighter color. In reality there is no observational difference in temperature between the vegetation in that spot and the surrounding vegetation.

This streak is evidence of the light’s glare on MODIS’ eye. The glare is much more common over water, which has a much higher natural reflectance than vegetation, as can be seen on the waters of Lago Calhora Bassa in western Mozambique, directly opposite the hot spot. On water, the glare appears grayish-silver. The hot spot is symmetrically opposed to the water glare; MODIS’ nadir (the point where the “eye” looks directly down) is exactly between the two streaks, roughly over Lake Kariba on the Zambia-Zimbabwe border.

This is a true-color Terra MODIS image from February 5, 2004.

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Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC

Published February 6, 2004
Data acquired February 5 - 5, 2004

Source:

Terra > MODIS