5 ms·

I know nothing about this sort of stuff, but if this were applied to cars, would there be an increased risk of temporarily blinding other drivers on a sunny day

I know nothing about this sort of stuff, but if this were applied to cars, would there be an increased risk of temporarily blinding other drivers on a sunny day?

aliqot 4y ago
How does it affect white balancing on traffic cameras?
HPsquared 4y ago
It won't shine any brighter than the light that's hitting it.
- lpghatguy 4y ago
  Like... the sun?
  - Dylan16807 4y ago
    Not like the sun. A white object is thousands of times less bright, because in every direction it emits an average of the light hitting it and the sun is such a small fraction of the sky.
- twawaaay 4y ago
  Still, snow can cause blindness: https://en.wikipedia.org/wiki/Photokeratitis https://en.wikipedia.org/wiki/Photokeratitis
tlb 4y ago
It reflects something like 98% of light instead of 90%, so the actual increase in reflected light isn't that big. Flat scattering surfaces are never blinding. The problem is with specular reflections off of shiny surfaces. Even though a shiny surface may only reflect a small fraction of incident light, it's all pointing in one direction which can dazzle observers.
- adrian_b 4y ago
  For the visible effect, you are right that there is little difference between 90% and 98%. For its intended application, reflecting 98% instead of 90% means absorbing 5 times less heat when under Sun light. That is a very large difference. A white paint with only 90% reflectance might cause negligible cooling, while one with 98% reflectance may cool a painted object to have a temperature less by more than 6 Celsius degrees in comparison with the air temperature. The cooling depends on the ratio between how much solar light is absorbed and how much far infrared light is emitted. So a cooling paint must be very white over the near infrared, visible and ultraviolet spectrum, but it must be black for the far infrared light which is emitted by the bodies at ambient temperature.

I know nothing about this sort of stuff, but if this were applied to cars, would there be an increased risk of temporarily blinding other drivers on a sunny day?

aliqot 4y ago

How does it affect white balancing on traffic cameras?

HPsquared 4y ago

It won't shine any brighter than the light that's hitting it.

lpghatguy 4y ago
Like... the sun?
- Dylan16807 4y ago
  Not like the sun. A white object is thousands of times less bright, because in every direction it emits an average of the light hitting it and the sun is such a small fraction of the sky.
twawaaay 4y ago
Still, snow can cause blindness: https://en.wikipedia.org/wiki/Photokeratitis https://en.wikipedia.org/wiki/Photokeratitis

tlb 4y ago

It reflects something like 98% of light instead of 90%, so the actual increase in reflected light isn't that big. Flat scattering surfaces are never blinding. The problem is with specular reflections off of shiny surfaces. Even though a shiny surface may only reflect a small fraction of incident light, it's all pointing in one direction which can dazzle observers.

adrian_b 4y ago
For the visible effect, you are right that there is little difference between 90% and 98%. For its intended application, reflecting 98% instead of 90% means absorbing 5 times less heat when under Sun light. That is a very large difference. A white paint with only 90% reflectance might cause negligible cooling, while one with 98% reflectance may cool a painted object to have a temperature less by more than 6 Celsius degrees in comparison with the air temperature. The cooling depends on the ratio between how much solar light is absorbed and how much far infrared light is emitted. So a cooling paint must be very white over the near infrared, visible and ultraviolet spectrum, but it must be black for the far infrared light which is emitted by the bodies at ambient temperature.