Question

If green light is perceived 5-7x brighter than other colors at the same power, and the sun’s peak wavelength output is green, why is the sun seen perceived more as yellow than green?

Answer 1

The perception of the Sun's color can vary depending on various factors, including atmospheric conditions and human perception. Although the Sun's peak wavelength output is in the green part of the spectrum, it is commonly perceived as yellow or white rather than green. This phenomenon can be explained by several reasons:

1. Atmospheric Scattering: The Earth's atmosphere scatters sunlight due to the presence of molecules and small particles. This scattering can cause a phenomenon known as Rayleigh scattering, where shorter wavelengths (blue and green) scatter more strongly compared to longer wavelengths (yellow and red). As a result, a significant portion of the green light from the Sun gets scattered, making the overall perception shift towards longer wavelengths, giving it a yellowish appearance.

2. Human Visual System: The human visual system is not equally sensitive to all colors. Our eyes are more sensitive to yellow wavelengths, particularly in bright conditions. The sensitivity of our eyes to different colors, along with the way our brain processes visual information, contributes to our perception of the Sun as yellow or white rather than green.

3. Color Temperature: The perception of the Sun's color can also be influenced by its color temperature. The color temperature of an object refers to the color it emits when heated. The Sun has a relatively high color temperature, around 5,500 to 6,000 Kelvin, which corresponds to a white or slightly yellowish color.

It's important to note that the perceived color of the Sun can vary depending on the time of day, atmospheric conditions, and personal perception. During sunrise or sunset, when the sunlight passes through a thicker portion of the atmosphere, it can appear more orange or red due to additional scattering and the filtering effect of the atmosphere.

In summary, while the Sun's peak wavelength output is in the green part of the spectrum, it is perceived more as yellow or white due to atmospheric scattering, the sensitivity of the human visual system, and the Sun's color temperature.