A Strobe light is a fixture that flashes a small pulse of light in relatively quick intervals (sometimes as quick as 200 miliseconds) These lights are used to achieve a type of effect called stroboscopic effect. This effect can make it seem as though certain objects are paused, or moving backwards. It can also make objects seem as though they are moving in slow motion. In theater they are a very easy way to simulate lighting.
Atmospheric Lighting is lighting accompanied by other effects usually fog, smoke, or mist of some kind, This lighting is achieved by shining lights through some sort of gaseous vapor.