7 ms·Air is mostly nitrogen. Nitrogen gas is blue. There.by alejohausner 7mo agoAir is mostly nitrogen. Nitrogen gas is blue. There.pbhjpbhj 7mo agoGo watch a video of nitrogen gas evaporating from liquid nitrogen ... tell me what colour you see?mjanx123 7mo agoOxygen is blue actually. That only contributes to the sky blueness a little tho.