JdM recently asked: ‘Why is it that colors seem more vivid on cloudy or overcast days?’
This is a great question and sort of a nice compensation for not having a sunny day, right?
But first, a little background on light:
Though sunlight looks white – it is actually composed of multiple wavelengths or ‘colors’ of light – including red, orange, yellow, green, blue indigo and violet. For you to ‘see’ individual colors, they need to be refracted or reflected.
As an aside, this video here explains refraction and how rainbows form.
But the science that we need to understand for this question is reflection.
When light hits surfaces, it can interact with the surface and is then scattered (also known as diffuse reflection). The light that is scattered is the ‘color’ of the surface material. In other words, objects appear to be certain colors because they reflect that color of light. Very simply put, green things reflect green light, blue things reflect blue light, and white things reflect pretty much all wavelengths of light equally.
Light can also be directly reflected from the object’s surface, and that light tends to remain the color of the light that hit it. In the case of sunlight, this is white light.
Objects in direct sunlight (or any bright light source) receive beams of parallel light from a single direction. In this situation, there is more direct reflection of the white light and thus colors look a bit more washed out.
On cloudy days, because of the interference of the atmosphere, sunlight tends to be more diffuse and scattered – in this case, we are seeing more diffusely reflected (‘colored’) light and less directly reflected light. So, this is why objects appear to be more vividly colored on cloudy days.
Happy Memorial Day, Friends. Stay safe and curious!