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user_area:water_reflectivity [2008/12/09 09:09]
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user_area:water_reflectivity [2011/08/11 16:35]
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| {{:user_area:norayleigh_ocean_gamma.png|}} | {{:user_area:norayleigh_ocean_gamma.png|}} |
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| It is clear that both contributions are important and we may safely assume that contribution 3 is important as well. | |
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| All the blue is gone. This clearly illustrates that the blue color of the ocean has nothing to do with wavelength-dependent reflectivity of the water surface, but is simply caused by the reflection of diffuse Rayleigh-scattered skylight (plus Rayleigh scattering of the reflected direct sun) by the ocean surface. In fact, we have three contributions: | All the blue is gone. This clearly illustrates that the blue color of the ocean has nothing to do with wavelength-dependent reflectivity of the water surface, but is simply caused by the reflection of diffuse Rayleigh-scattered skylight (plus Rayleigh scattering of the reflected direct sun) by the ocean surface. In fact, we have three contributions: |
| Both contributions are relevant for the result, but it appears that the direct atmospheric contribution is actually higher than the reflection of the atmosphere by the ocean surface, except at the edges. This has probably to do with the fact that the reflectivity of clean water is generally very small, except for low incidence or reflection angles. | Both contributions are relevant for the result, but it appears that the direct atmospheric contribution is actually higher than the reflection of the atmosphere by the ocean surface, except at the edges. This has probably to do with the fact that the reflectivity of clean water is generally very small, except for low incidence or reflection angles. |
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| This calculations were done immediately after a Christmas party of the [[http://www.espace-tum.de/|ESPACE Master's Program]] at the Technical University of Munich where [[http://en.wikipedia.org/wiki/Ulrich_Walter|Prof. Ulrich Walter]] reported about his experiences in space during the [[http://en.wikipedia.org/wiki/STS-55|STS-55 Mission]] (aka D-2 Mission). We were wondering where the blue color of the Earth comes from and after a few cups of [[http://en.wikipedia.org/wiki/Mulled_wine|Gluehwein]] these calculations were made (yes, libRadtran is really that easy to use!). As an experimental confirmation, Ulrich Walter provided this picure taken from the International Space Station which is remarkably close to the simulation. Well, except for the clouds, and I guess without the Gluehwein we would have been able to even include the clouds in the calculation: | This calculations were done immediately after a Christmas party of the [[http://www.espace-tum.de/|ESPACE Master's Program]] at the Technical University of Munich where [[http://en.wikipedia.org/wiki/Ulrich_Walter|Prof. Ulrich Walter]] reported about his experiences in space during the [[http://en.wikipedia.org/wiki/STS-55|STS-55 Mission]] (aka D-2 Mission) and showed many exciting pictures of the Earth taken from space. We were wondering where the blue color of the Earth comes from and after a few cups of [[http://en.wikipedia.org/wiki/Mulled_wine|Gluehwein]] these calculations were made (yes, libRadtran is really that easy to use!). As an experimental confirmation, Ulrich Walter provided this picure taken from the International Space Station which is remarkably close to the simulation. Well, except for the clouds, and I guess without the Gluehwein we would have been able to even include the clouds in the calculation: |
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| {{:user_area:earth_wide_angle_view_iss007_800.jpg|}} | {{:user_area:earth_wide_angle_view_iss007_800.jpg|}} |
