query: What's the temperature water boils at?
passage: Boiling point
The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high pressure has a higher boiling point than when that liquid is at atmospheric pressure. For example, water boils at 100°C (212°F) at sea level, but at 93.4°C (200.1°F) at 1,905 metres (6,250ft) [3] altitude. For a given pressure, different liquids will boil at different temperatures.
passage: Mercury-in-glass thermometer
When Celsius decided to use his own temperature scale, he originally defined his scale "upside-down", i.e. he chose to set the boiling point of pure water at 0°C (212°F) and the freezing point at -100°C (-32°F).[2] One year later, Frenchman Jean-Pierre Christin proposed to invert the scale with the freezing point at 0°C (32°F) and the boiling point at 100°C (212°F).[3] He named it Centigrade (100 grades).