>> In tests, it cooled surfaces by 4.5C below the ambient temperature, even in strong sunlight. I am not in phisics but AFAIU in order to "cool" one have to remove energy from the object being cooled. So the paint would have to actively emitt energy and well the best emitters are not while, are they? Perfect black body comes to mind but this probably would not work well in direct sunlight?
So can you explain the process by which the white paint is able to cool below ambient? Is this Maxwell's demon th
So can you explain the process by which the white paint is able to cool below ambient? Is this Maxwell's demon then;-)?
Thermodynamically, any surface that is poor at absorbing light will also be poor at emitting it. But that can still vary by wavelength.
The paint is highly reflective in visible and UV light. But not IR. It will absorb IR and also emit IR.
Sunlight is mostly visible light, which is reflected. Ambient heat is mostly IR, which is emitted. So the net result is cooling below the ambient temperature of other surfaces.
it..cools? (Score:3)
>> In tests, it cooled surfaces by 4.5C below the ambient temperature, even in strong sunlight.
I am not in phisics but AFAIU in order to "cool" one have to remove energy from the object being cooled. So the paint would have to actively emitt energy and well the best emitters are not while, are they? Perfect black body comes to mind but this probably would not work well in direct sunlight?
So can you explain the process by which the white paint is able to cool below ambient? Is this Maxwell's demon th
Re:it..cools? (Score:5, Interesting)
So can you explain the process by which the white paint is able to cool below ambient? Is this Maxwell's demon then ;-)?
Thermodynamically, any surface that is poor at absorbing light will also be poor at emitting it. But that can still vary by wavelength.
The paint is highly reflective in visible and UV light. But not IR. It will absorb IR and also emit IR.
Sunlight is mostly visible light, which is reflected. Ambient heat is mostly IR, which is emitted. So the net result is cooling below the ambient temperature of other surfaces.