Supercooling
The process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid is referred as supercooling also known as undercooling. The process of going from liquid to solid is exothermic. This means that as a liquid changes into solid, heat is released.
Water normally freezes at 0 degrees Celsius or 32 degrees Fahrenheit. The freezing and the cooking temperature of water can among others be influenced by increasing the air pressure. The higher the pressure is the lower the freezing temperature. There are some other factors that influence the freezing temperature like adding impurities. A great example is salt that is used to lower the freezing temperature of water.
If a liquid is cooled below its freezing point it will crystallize in the presence of a seed crystal or nucleus which a crystal structure can form around. A crystal or nucleus can be a dust particle for example. If the seed crystals or the nucleus aren't around the liquid won't go to a solid state. But there is a maximum temperature, this is -42oC / -44oF. If its cooled to this temperature the water will freeze, despite of any seed crystals or nucleus are arround.
