What defines spectral reflectance?

Spectral reflectance is defined as the ratio of reflected radiation to incoming radiation, which is fundamental in remote sensing and understanding how surfaces interact with light. This measurement helps determine how much of the light that strikes a surface is reflected back, and it varies across different wavelengths of light.

This characteristic is crucial for various applications, such as identifying materials based on their spectral signatures, assessing vegetation health, or analyzing land cover types. By quantifying reflectance, scientists can analyze and interpret data captured by sensors on satellites or aerial platforms to gain insights about the Earth's surface.

In contrast, the first option refers to the total amount of light absorbed rather than reflected, while the third option mentions the emission of radiation, which is different from reflectance. Lastly, scattering of sunlight by the atmosphere pertains to atmospheric effects rather than the properties of surface materials themselves. Therefore, the definition attached to the reflectance specifically emphasizes the measurement relative to incoming light, making it the correct choice.