I have a black car and a white car. It’s a sunny, 95-degree day.
The white car’s paint is warm to the touch while obviously the black car’s paint is extremely hot to the touch. I get that the black paint is absorbing most of the the sun’s light energy, which gets converted to heat. But the white paint is clearly being warmed by the sun to some degree as well. Is this because the white paint is not an absolutely pure white that reflects back 100% of the sun’s light energy, i.e., it still absorbs some small amount? Or is the warmth I’m feeling on the white car’s paint basically just the air temperature?
In: Physics
It’s because it is not truly reflecting back 100% of the light.
It’s reflecting back a lot of it, but not all of it. Even mirrors do not reflect back 100% of the light that hits them.
First, the metal car will be at ambient temperature, which is going to feel hot to the touch. Being metal, it will feel hotter than something like plastic at the same temperature, since that temperature is above your skin temperature.
That said, neither black nor white paint is perfect. In fact they’re not even particularly close to perfect.
If it was reflecting all the light, it would be shiny like unpainted metal.
Black absorbs all colors of light equally, just not all the light.
White absorbs all colors of light equally, but not a majority of light.
White, grey, and black are all shades of the same color.
1. The car absorbs heat from the environment. At night, it will be the same temperature as the air around it, when it’s 100° outside during the daytime, even if you parked your car in the shade, the surface would be 100°.
2. Yes, the white paint isn’t reflecting 100% of the light
3. Light isn’t the only thing the sun radiates, it also radiates infrared radiation.
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