Question

We know that the sky appears blue due to Rayleigh scattering. But nevertheless, we are able to see white objects. I suppose it is because white objects reflect blue light so weakly that it is overwhelmed by the reflected white light, and that is why it is not seen. Here is a winter scene on a day with bright sun and a blue sky. Note how the shadowed regions are blue due to the scattered sky light. Meanwhile the sunlit regions are white. The reason they look white is that the reflected sunlight is significantly brighter than the sky light: were you to check the light spectrum it would deviate a bit from sunlight by having some more blue light, but it is not noticeable enough to the eye or camera under these conditions (mostly due to the brightness, but also due to the brain doing a bit of colour compensation). You seem to be imagining a scenario where a white object is lit by scattered blue light from the entire sky but not lit by the white light from the sun. One experiment might be to examine the color of an object as it is lowered down into a well, so that the sky provides the only illumination. But color perception is a complicated process that has as much to do with biology as with physics. In a comment, you clarify: In my scenario, the white object receives the white light from the sun and also the scattered blue light. My question is why we don't see the white color as bluish. This is because direct sunlight is approximately a zillion times brighter than the rest of the sky. If you have a magnifying glass (say, at your local drugstore), you can hold a sheet of white paper at the focal distance, and you'll get an inverted image of the sky or trees or buildings or whatever on the paper. Now orient this handmade camera so that your image includes the sun. The sunlight is so much more intense that you may catch the paper on fire.

Answer 1

White objects appear white because they reflect all wavelengths of sunlight, which is much more intense than the blue light scattered by the sky, leading our eyes and brain to perceive them as white due to the uniform mixture of colors in sunlight and color compensation.

Step-by-step explanation:

The reason we see white objects as white and not bluish, even though the sky appears blue due to Rayleigh scattering, lies in the intensity and composition of sunlight. Sunlight, which is composed of a spectrum of colors including red, orange, yellow, green, blue, and violet, appears white to us because it contains a fairly uniform mixture of all visible wavelengths. When sunlight hits a white object, it reflects all these wavelengths roughly equally. Because direct sunlight is significantly brighter than scattered light from the sky, the additional blue light from the sky is not typically enough to perceptibly change the color of a white object in sunlight. Our eyes and brain perceive it as white, thanks in part to the psychological process of color compensation.

Color perception varies depending on illumination conditions, and objects absorb or reflect different wavelengths to display their colors. Although sunlight is a bit yellow due to its mixture of wavelengths, it contains all colors within the visible spectrum, which is why it looks white. White objects reflect all wavelengths, contributing to their white appearance even under the influence of blue sky light.