A fog machine is a device which emits a dense vapor that appears similar to fog. This artificial fog is most commonly used in professional entertainment applications, but smaller, more affordable fog machines are becoming common for personal use. Fog machines can also be found in use in a variety of industrial, training, and some military applications. Typically, fog is created by vaporizing proprietary water and glycol-based fluids. This fluid (often referred to colloquially as fog juice) vaporizes or atomizes inside the fog machine. Upon exiting the fog machine and coming into contact with the moisture in the outside air the vapor condenses, resulting in a thick visible fog.
