The triple point for water can be explained as the temperature-pressure condition at which all the phases of water are in the state of equilibrium. This means that all three states of water namely solid, liquid and water coexists in thermodynamic equilibrium. This plays an important role in the identification of compounds. The value of the triple point of water is approximately 0.01°C.
In the polar and the sub-polar region, the temperature and pressure are normally lower than it is in the equatorial and mid-latitude regions. The point where the pressure and temperature allows the water to appear in all its three phases is the transition point between the sub-polar and polar region. This transition point is known as the triple point.
