"Boiling" is really a liquid turning into a gas [1]. This happens when the liquid has enough energy to transition into a different state [2], that is, when the

"Boiling" is really a liquid turning into a gas [1]. This happens when the liquid has enough energy to transition into a different state [2], that is, when the vapor pressure of the liquid [3][4] equals the surrounding pressure. Thus at the pressure given in the article (say, 0.5 psi), water can boil at around 79.6 °F / 26.4 °C [5]. [1] http://en.wikipedia.org/wiki/Boiling_point http://en.wikipedia.org/wiki/Boiling_point [2] http://en.wikipedia.org/wiki/Heat_of_vaporization http://en.wikipedia.org/wiki/Heat_of_vaporization [3] http://en.wikipedia.org/wiki/Vapor_pressure http://en.wikipedia.org/wiki/Vapor_pressure [4] A solid can "boil" too, but it's called sublimation. http://en.wikipedia.org/wiki/Sublimation_(physics) http://en.wikipedia.org/wiki/Sublimation_(physics) [5] http://www.engineeringtoolbox.com/boiling-point-water-d_926.html http://www.engineeringtoolbox.com/boiling-point-water-d_926....