The Fascinating History of Temperature Scales

For most of human history, temperature was purely subjective. Something was hot, warm, cool, or cold based on how it felt. The development of thermometers and temperature scales transformed temperature from a qualitative sensation into a precise measurement.

Daniel Gabriel Fahrenheit was a German physicist working in the Netherlands. In 1724, he introduced the scale that bears his name. He set 0°F as the temperature of a mixture of ice, water, and ammonium chloride, and 96°F as human body temperature.

Water freezes at 32°F and boils at 212°F—a span of 180 degrees. Fahrenheit wanted to avoid negative numbers in everyday weather measurement.

Anders Celsius was a Swedish astronomer who proposed his temperature scale in 1742. His approach was based on water: 0°C is freezing and 100°C is boiling. The 100-degree span made calculations simple and fit perfectly with the metric system.

William Thomson (Lord Kelvin) proposed an absolute temperature scale in 1848 based on absolute zero—the point where all molecular motion ceases. Absolute zero is -273.15°C or -459.67°F. The Kelvin scale is essential for scientific calculations.

Fahrenheit remains popular in the US for everyday use. Celsius dominates most of the world and scientific work. Kelvin is the standard for physics and chemistry.