It is important to note that there is a relationship between pressure and temperature. That is, the higher the pressure, the higher the temperature. The lower the pressure, the lower the temperature. In small attitudes, as regions located at sea level, the atmospheric pressure is high. This is because the amount of air that weighs on them is great. As a consequence, the temperature in these regions is higher than in the high regions, such as mountain tops, where pressure and temperature are low. These factors interfere with water boiling processes. Example: Water under normal atmospheric pressure at sea level boils at 100 ° C. Already at a high altitude, 3,500m, for example, the water boils around 90 ° C. That is, when the pressure is low, the water begins to boil at a lower temperature.
The water may also boil above 100 ° C provided that it is subjected to a pressure greater than atmospheric pressure at sea level. Take, for example, a pressure cooker. The boiling point of the water in a pressure cooker is greater than 100 ° C because the discharge valve pin prevents to some extent the outlet of the vapor, causing the inner pressure of the pan to be greater than the external pressure. This shows that the evaporation temperature of a fluid changes as the pressure to which it is subjected varies.
