I too was puzzled, decided to get to the root of this phenomenon, and found out the cause of sky turning yellow at night- it is due to neon light bulbs on factory premises and streets. The light emitted by these heavy-duty bulbs gets reflected by clouds in the sky, resulting in the yellow/orange hue. To the best of my knowledge, this is the reason for sky turning yellow/orange at night. Correct me if my observation is wrong.
It is actually the light from nearby cities or if you live in the city you'll see the sky turn yellow. You don't experience this when you go to small towns or country side.
Umm can you take a pic of it and post it??that might help.
:( Ive never seen it that way. I guess I always miss it.
It may be pollution in the sky.