why does water boil below 100 c at high elevations
High-altitude cooking High-altitude cooking is the opposite of pressure cooking in that the boiling point of water is lower at higher altitudes due to the decreased atmospheric pressure. This may require an increase in cooking times or temperature and alterations of recipe ingredients. For home cooking, this effect becomes relevant at altitudes above approximately 2,000 feet (610 m). At that altitude, water boils at approximately 208°F (98°C) and adjustments sometimes need to be made to compensate for the reduced air pressure/water boiling point.
Geyser A geyser (US: /ˈɡaɪzər/; UK: /ˈɡiːzər/ or /ˈɡaɪzər/[1][2]) is a spring characterized by intermittent discharge of water ejected turbulently and accompanied by steam. As a fairly rare phenomenon, the formation of geysers is due to particular hydrogeological conditions that exist only in a few places on Earth. Generally all geyser field sites are located near active volcanic areas, and the geyser effect is due to the proximity of magma. Generally, surface water works its way down to an average depth of around 2,000 metres (6,600 ft) where it contacts hot rocks. The resultant boiling of the pressurized water results in the geyser effect of hot water and steam spraying out of the geyser's surface vent (a hydrothermal explosion).