A chick hatching from an egg. The chicken or the egg causality dilemma is commonly stated as which came first: the chicken or the egg?. The dilemma stems from the observation that all chickens hatch from eggs and all chicken eggs are laid by chickens.
Unpolarized light can also become polarized when it is scattered in air (also known as Rayleigh scattering). This occurs due to the fact that the EM waves cause the electron in air to vibrate, producing radiation and causing polarization of the light.
As light continues to move though the atmosphere, yellow wavelengths are scattered leaving orange wavelengths. Further scattering of orange wavelengths leaves red as the predominate color of sunlight. Therefore, near sunrise and sunset, a cloud's color is what sunlight color it receives after Rayleigh scattering.