Celsius and Fahrenheit are the most common temperature measurements.
The centigrade temperature scale, more properly known as the Celsius temperature scale, is a scale for measuring temperatures that is based on the behavior of water at normal pressure. This scale is widely used in much of the world to express temperatures, with some hardy countries using the Fahrenheit temperature scale. The Celsius scale is also used as a reference for the Kelvin scale, which is used in the scientific community.
On the Celsius scale, the freezing point of water is set to 0 degrees and the boiling point of water is set to 100 degrees. The scale is named after Anders Celsius, a Swede who developed an early version of this scale. Somewhat confusingly, early versions of the Celsius temperature scale were reversed, with water freezing at 100 degrees and boiling at 0 degrees. Linnaeus is widely considered to be the first to use 0 as the freezing point.
The scale was widely known as the Celsius temperature scale until 1948, when it was changed to “Celsius” to avoid confusion with a unit of measurement also called Centigrade. However, many people continue to use the term “Centigrade temperature scale,” especially members of the general public who are not in the habit of consulting the proceedings of the General Conference on Weights and Measures. Both of these uses are widely known, though scientists may cringe at hearing “Celsius temperature scale.”
The basic concept of the Celsius scale was adapted during the development of the Kelvin scale. The Kelvin temperature scale uses absolute 0, the theoretically coldest possible temperature, as the 0 point, making the freezing point of water 273.15 kelvins (32 degrees Fahrenheit). The 100-point distance between freezing and boiling is maintained on the Kelvin scale, so water boils at 373.15 kelvins (212 degrees Fahrenheit). By the way, a kelvin is a unit of measurement, so temperatures are given in “kelvins”, not “kelvins”, and by convention, “kelvin” is not capitalized when giving temperature measurements, although yes when talking about the Kelvin Scale.
It is not uncommon to find a thermometer that gives measurements in both Fahrenheit and Celsius, due to the convenience of converting between the two systems, particularly in the United States. It may be helpful to know that a Fahrenheit degree is 5/9 of a Celsius degree, and the quickest way to approximate Celsius temperatures in Fahrenheit is to double and add 32, although the actual formula is (°C × 1.8) + 32 .