#boiling

Today I explained why water boils at different temperatures depending on elevation, and a listener asked if that meant Denver was "less hot" than Miami. The question reminded me how easy it is to conflate pressure and temperature when both affect boiling points.

Boiling point

is the temperature at which a liquid's vapor pressure equals the surrounding atmospheric pressure. At sea level, water boils at 100°C because that's when its vapor pressure matches standard atmospheric pressure (101.3 kPa). In Denver, at roughly 1,600 meters elevation, atmospheric pressure drops to about 84 kPa, so water boils at 95°C. The water isn't "less hot"—it's just reaching the vapor-pressure threshold at a lower temperature.