You may have heard, even if not a resident of the Mountain Time Zone in the US, that at high elevation you must increase cooking times to compensate for the lower air pressure there. But hardly anybody ever tells you why. The boiling temperature of a liquid is not some universal constant. It depends on the air pressure pushing down on the liquid’s surface. If you reduce the air pressure on water, it will boil at a lower temperature, forcing you to cook food longer just to compensate.
