Next Steps?

[razvanc-r]

Alright, just in case you might be interested in this stuff :) or any other around. The reason why this is happening, that is why we have warm lights & cool shadows in "most situations" which is basically another way of saying "the usual sunny day" is... physics.

The sky is blue due to something called reyleigh scattering, that is, small particles & molecules (which are in majority in the atmosphere) scatter blue, ultraviolet and all that part of the spectrum better than other colors. They also scatter in all directions more or less equally, regardless of the incoming light (sun light in this case) angle to the particle. On the other hand there's this other thing called mie scattering which is scattering on larger particles (less in atmosphere compared to the small particles/molecules) and this is more affecting orange/red/infra-red spectrum and interestingly enough, the incoming light that hits these larger particles gets scattered mostly... in the same direction, small diagram:
..................................\ /
incoming sun light ----> O ---> reflected light (yeah... following the same line as the incident light)
................................../ \
This is the reason why we have a blue sky with an bright (yellowish) sun light. The reflected light from the diagram is also more reddish as previously mentioned.

This is also the reason why during evenings we have an orange/red sky. Because sun light travels a larger portion of the atmosphere, interacting with more larger particles and mie scattering takes over reyleigh scattering and the sky appears orange instead of blue (also in reality sky is mostly violet/ultra-violet but our eyes aren't sensitive enough to pick that up).

So for painting now, what this means is that shadow area receives light more from the environment (this being mostly sky) so it appears blueish, while the bright parts which are in direct sun light appear yellow/orange/red because they are directly influenced by sun-light, so not so much by the sky & environment bounce light.

So obviously this describes the typical sunny "usual" afternoon. On mars for example it's exactly the other way around, the sky is usually orange/red due to the high concentration of larger particles in the thin atmosphere that it has, also because of their chemical composition of course and natural color. And during evenings the sky is usually blue-ish, when reyleigh scattering becomes more important. The blue part surrounds the sun and gradually goes towards orange/red, so it's not as strong as the mie scattering on earth for example, during sun sets. So in your typical "usual" afternoon on mars you'd have mostly orange/redd-ish shadows and the sunny parts will have a very very slight blue tint in it.

Of course, on top of all this, there comes in stuff like sub-surface scattering, muscle color, vanes, the way our eyes perceive boundaries between hot/cool colors etc. And just to drive the point across, this *only* happens during the typical sunny afternoon. In other settings such as garages for example, you'd have to take in account the color of the neon light (cool usually) and think about the bounce light (say for example is the subject near a colorful red/green/whatever car?) and so on :).

Hope this was helpful or at least entertaining :P