Instead, there are different colors of light that move in different ways. Our atmosphere is not just empty air, either. So far as light is concerned it acts like a prism and causes light to refract. Since the different colored lights curve at different speeds, this accounts for how we can see this green flash during times when the sun sets or rises. In some cases, the atmospheric conditions around the viewer will cause different illusions to appear as well, like a flashing ray of light or a stretched-out and shaky mirage.
The easiest places to see the green flash are those where the horizon is not blocked by buildings or other large objects. The ocean, above a layer of clouds, or on top of a mountain are all good examples. Green flashes do not last very long so it can be difficult to see them. At most, they last for a few seconds.
Nuclear winter is a terrifying possible effect of nuclear warfare. Basically what would happen is that the dust and soot from the fires started by many nuclear bombs going off would leak into the far upper atmosphere. Due to being heated by sunlight after reaching the upper atmosphere, these clouds of debris would then rise even further, above normal weather conditions. Since they could no longer be washed away by rain or blown away by the wind, these clouds would stay in the air for many years, causing temperatures to drop around the earth. If there had been a very large nuclear war, the temperature change could be quite drastic, or it could be as small as a few degrees in the case of a smaller conflict.
In addition to causing cooler temperatures, a nuclear winter would have an effect on rainfall, lowering it by up to 75% in some areas in the three months immediately following the cloud entering the atmosphere. Nuclear Winter would also have a devastating effect on the worlds ozone layer, decreasing it by as much as 20% overall across the globe. This would increase the amount of UV radiation that got