History and Development of the Celsius Scale
– Celsius scale created by Anders Celsius in 1742
– Originally reversed scale with 0 as boiling point and 100 as freezing point
– Jean-Pierre Christin inverted the scale in 1743
– Carl Linnaeus reversed the scale again in 1744
– Various physicists and instrument makers contributed to the development of the scale
– Celsius scale was in sporadic, non-scientific use before 1948
– The 1948 adoption of Celsius accomplished three objectives
– Anders Celsius gave the Celsius scale its modern form in 1742
– Jean-Pierre Christin inverted the fixed points on the Celsius scale in 1743
Centigrade vs Celsius
– Centigrade scale used in the 19th century
– Term ‘centigrade’ also used for angular measurement
– Degree Celsius formally adopted in 1948 to avoid confusion
– Celsius commonly used in scientific work
– Centigrade still commonly used in English-speaking countries
Common Temperatures and Conversions
– Celsius scale used for phase transitions at standard atmosphere
– Temperatures defined by standard measurements or approximations
– Freezing point of water at 0°C
– Boiling point of water at 100°C
– Other common temperatures include room temperature (around 20-25°C) and body temperature (around 37°C)
– Celsius can be converted to Kelvin by adding 273.15
– Celsius can be converted to Fahrenheit using the formula (9/5 * Celsius) + 32
– Kelvin is the SI base unit for temperature
– Fahrenheit scale still used in the United States, some island territories, and Liberia
– Conversion formulas allow for easy conversion between Celsius, Kelvin, and Fahrenheit
International Standards and Usage
– Celsius scale defined by absolute zero and triple point of water
– Definition refers to Vienna Standard Mean Ocean Water (VSMOW)
– Kelvin scale redefined in 2019 based on the Boltzmann constant
– Triple point of water now a measured value, not a defined value
– Degree Celsius remains exactly equal to the kelvin (0°C = 273.15K)
– The degree Celsius has been the only SI unit whose full unit name contains an uppercase letter since 1967
– Different languages and publishing houses may have different typographical rules
– Unicode provides the Celsius symbol at code point U+2103 DEGREE CELSIUS
– The use of the Celsius symbol is discouraged, and it is better to represent degrees Celsius °C with a sequence of U+00B0 DEGREE SIGN + U+0043 LATIN CAPITAL LETTER C
– The degree Celsius is suitable for expressing specific temperatures along its scale
– It is also suitable for expressing temperature intervals, which are differences between temperatures or their uncertainties
Coexistence of Kelvin and Celsius Scales
– In science and engineering, the Celsius scale and the Kelvin scale are often used together
– The magnitude of the degree Celsius is equal to that of the kelvin
– The use of SI-prefixed forms of the degree Celsius to express a temperature interval is not well adopted
– Simultaneously using °C and K remains widespread in the scientific world
– Decision no. 3 of Resolution 3 of the 13th CGPM allows expressing a temperature interval in degrees Celsius
– The Celsius scale’s definition changed to use the triple point of water and later the Boltzmann constant
– The numerical values of the Celsius scale remained identical to the prior definitions
– The melting and boiling points of water are no longer part of the definition of the Celsius scale Source: https://en.wikipedia.org/wiki/Celsius
The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the closely related Kelvin scale. The degree Celsius (symbol: °C) can refer to a specific temperature on the Celsius scale or to a difference or range between two temperatures. It is named after the Swedish astronomer Anders Celsius (1701–1744), who proposed the first version of it in 1742. The unit was called centigrade in several languages (from the Latin centum, which means 100, and gradus, which means steps) for many years. In 1948, the International Committee for Weights and Measures renamed it to honor Celsius and also to remove confusion with the term for one hundredth of a gradian in some languages. Most countries use this scale (the Fahrenheit scale is still used in the United States, some island territories, and Liberia).
| degree Celsius | |
|---|---|
 A thermometer calibrated in degrees Celsius, showing a temperature of −17 °C | |
| General information | |
| Unit system | SI |
| Unit of | temperature |
| Symbol | °C |
| Named after | Anders Celsius |
| Conversions | |
| x °C in ... | ... corresponds to ... |
| SI base units | (x + 273.15) K |
| Imperial/US units | (9/5x + 32) °F |
Throughout the 19th century, the scale was based on 0 °C for the freezing point of water and 100 °C for the boiling point of water at 1 atm pressure. (In Celsius's initial proposal, the values were reversed; the boiling point was 0 degrees and the freezing point was 100 degrees).
Between 1954 and 2019, the precise definitions of the unit degree Celsius and the Celsius scale used absolute zero and the triple point of water. Since 2007, the Celsius scale has been defined in terms of the kelvin, the SI base unit of thermodynamic temperature (symbol: K). Absolute zero, the lowest temperature, is now defined as being exactly 0 K and −273.15 °C.
