Image Envision Home     Stock Images     Download Media     Cart     FAQs    
All     3d     Clipart     Illustrations     Historical     Objects     Photochromes     Photomontages     Photos  
TERMS OF USE: This free image can only be used for non-commercial, personal website use only. THIS IMAGE CANNOT BE used in galleries, downloaded to your computer, posted on sites for others to use, manipulated, downsized, or upsized. If you are confused about the terms of use or have any questions then contact us before using the image.

Free Picture: Seasonal Changes in Earth's Surface Albedo

Free Picture of Seasonal Changes in Earth

Image URL  
Forum BB  

About 50 million square kilometers of the Earth's terrestrial surface undergo a transition each year from freeze to thaw, thus setting off a series of global biospheric processes. Much of this activity can be detected by the temporal changes in the amount of sunlight reflected by the Earth's surface at various wavelengths. A quantitative measure of this reflected sunlight is described by the albedo, which is the fraction of sunlight reflected by a surface area to that incident on the surface area in all directions, typically in a given spectral band. The surface albedo can vary between zero (all incident sunlight is absorbed at the surface and none is reflected) and one (all incident sunlight is reflected from the surface and none is absorbed). Fresh snow is an example of a surface type with an albedo close to one in the visible region of the solar spectrum whereas deep clean ocean water has an albedo that is close to zero. Five years of global surface albedo data are now available as summary maps from NASA's Multi-angle Imaging SpectroRadiometer (MISR). The globes in the image show a particular kind of albedo, formally known as Directional Hemispherical Reflectance (DHR), in which all scattering effects from the atmosphere are removed. Thus the sunlight incident on any part of the global surface is uniquely directional, coming only from the location of the sun in the sky and with no multidirectional sunlight created by scattering in the atmosphere. The first and third line of globes show MISR blue, green, and red band DHR, combined to create a natural color DHR. The second and fourth line of globes show DHR-PAR, that DHR for the sunlight band containing only those wavelengths used in photosynthesis (400 - 700 nanometers), which are absorbed by vegetation. The sunlight in this spectral region is known as photosynthetically active radiation (PAR), thus the label DHR-PAR for the associated albedo. A heavily vegetated surface area will therefore have a small DHR-PAR va

albedo, earth, jpl, nasa, season, seasons, seasonal changes in earths surface albedo,  free photography,  free photo,  free photos,  free picture,  free pictures,  free image,  free images

Similar Free nasa Pictures
Lake Carnegie
Astronaut Neil Alden Armstrong
Astronaut Tracy Ellen Caldwell
Astronaut John Elmer Blaha
Astronaut Douglas Harry Wheelock
Astronaut Steven Wayne Lindsey
Astronaut Laurel Blair Salton Clark
Astronaut Carlos Ismael Noriega
Astronaut Paul Lockhart
Astronaut Kenneth Duane Bowersox
Astronaut Barbara Radding Morgan
Cosmonaut Valery Victorovich Ryumin

Privacy       Contact       About       Image Collections       Artist Login
Copyright © 2005-2013 Image Envision LLC   All Rights Reserved       Additional resources: Clipart, Logos