Three ancient comes gather on a heath. Thunder rolls, lightning flashes. Wispy, white mist swirls. Bit it is an illusion for a theatre performance of Macbeth.
One of the simplest way to create ‘fog’ or mist is with dry ice – solid carbon dioxide (CO2). Carbon dioxide is a gas which turns liquid when cooled under pressure. If the pressure is removed and the low temperature maintained , CO2 solidifies into snowlike crystals which can be compressed into dry ice cakes.
Then, if a lump of the substance is removed from its refrigerated container and immersed in hot water, it rapidly turns to mist. The fog-making process can be better controlled by a dry-ice machine. This consists of a closed tank with an opening from which the vapour billows. A hose attached to the opening is used to direct the ‘fog’.
For a lighter fog, which will hover, non-toxic oil is vaporised by a heating element in a fog machine. Fog produced from oil tends to linger longer than dry-ice mist which vanishes quickly.
Picture Credit : Google