Update get_ground_diffuse description #1883
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pvlib/irradiance.py
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| @@ -542,7 +542,8 @@ def poa_components(aoi, dni, poa_sky_diffuse, poa_ground_diffuse): | |||
| def get_ground_diffuse(surface_tilt, ghi, albedo=.25, surface_type=None): | |||
| ''' | |||
| Estimate diffuse irradiance from ground reflections given | |||
| irradiance, albedo, and surface tilt. | |||
| irradiance, albedo, and surface tilt. The ground is assumed to | |||
| be isotropic and reflections are Lambertian. | |||
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| be isotropic and reflections are Lambertian. | |
| be horizontal and flat, and reflections are Lambertian. |
I don't think the word isotropic is appropriate here.
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Adding "horizontal and flat" is a good idea. isotropic refers to properties such as albedo
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If you want to use the word isotropic I would suggest something more like: the surface is Lambertian and the reflected radiance is isotropic.
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+1 on this clarification |
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@kandersolar @AdamRJensen please take a look, moved this forward to v0.10.4 |
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@cwhanse Do you have a source that explains the difference between isotropic and Lambertian? |
If a surface is Lambertian, then reflected radiance is isotropic. https://en.wikipedia.org/wiki/Lambertian_reflectance |
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A surface (or a material) can also be isotropic, which means that its properties don't depend on position or direction. |
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This PR looks good to me! |
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Maybe irrelevant but the opposite of Lambertian is “specular” like a mirror, a specular surface only reflects light in a single direction: https://en.m.wikipedia.org/wiki/Specular_reflection. A Lambertian surface reflects light in more than one direction |
docs/sphinx/source/whatsnewfor all changes. Includes link to the GitHub Issue with:issue:`num`or this Pull Request with:pull:`num`. Includes contributor name and/or GitHub username (link with:ghuser:`user`).remote-data) and Milestone are assigned to the Pull Request and linked Issue.There exist several methods in the literature for estimating ground-reflected diffuse irradiance. Thus, the pvlib method should clearly state that it is based on isotropic ground reflections (which is the most common method)