When two air masses with different characteristics meet what happens

If the boundary between the cold and warm air masses doesn't move, it is called a stationary front. The boundary where a cold air mass meets a cool air mass under a warm air mass is called an occluded front. At a front, the weather is usually unsettled and stormy, and precipitation is common.

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.