What is the Difference Between Albedo and Reflectance?

Albedo and reflectance are both related to the reflection of light, but they have different meanings and applications. Here are the main differences between them:

1. Definition: Albedo is the percentage of solar energy striking a surface that is reflected away from the Earth, while surface reflectance is the ratio of the amount of light not absorbed by a surface to the amount of light striking the surface.
2. Scope: Albedo is primarily used for visible and infrared light, whereas reflectance refers to any form of reflected radiation.
3. Applications: Albedo is more often used in astronomy and climate science, whereas reflectance is more widely used in various scientific and engineering fields.
4. Material Thickness Dependence: Albedo does not depend directly on material thickness, whereas reflectance does depend on material thickness.
5. Spectral Range: Albedo is commonly used to refer to both visible and infrared light reflection, while reflectance can refer to any form of radiance that is reflected.

In summary, albedo specifically refers to the measure of how much light is reflected from a surface, primarily in the context of visible and infrared light, while reflectance is a more general term that can refer to any form of reflected radiation independent of thickness or material.

Comparative Table: Albedo vs Reflectance

Here is a table comparing the differences between albedo and reflectance:

In summary, albedo is a specific measure of a surface's reflectivity, primarily used for visible and infrared light in astronomy and climate science. Reflectance, on the other hand, is a more general term referring to the ratio of reflected radiant flux to incident radiant flux on a surface, independent of the medium or material thickness.