The degree Celsius (symbol: ° C) designates the temperature unit, named after the Swedish astronomer Anders Celsius (1701–1744), who was the first to propose it in 1742. The Celsius temperature scale was designed that the freezing point (freezing) of the water corresponds to zero, and the evaporation point corresponds to the value 100, observed at a standard atmospheric pressure.
As there are 100 graduations between these two reference points, the original term for this system was either centigrade (100 parts) or hundredths. In 1948, the name of the system was officially changed to Celsius during the 9th General Conference on Weights and Measures (CR 64), both in recognition of Celsius and to eliminate the confusion caused by the conflict in the use of the SI centi prefixes. Therefore, it is not convenient to say “degree centigrade”, but rather, “degree Celsius”.
While the water freeze and evaporation values are approximately correct, the original definition is not appropriate as a formal standard: it depends on the definition of standard atmospheric pressure, which in turn depends on the temperature definition itself. The current official definition of degree Celsius defines 0.01 ° C as the triple point of water, and 1 degree Celsius as being 1 / 273.16 of the temperature difference between the triple point of water and absolute zero. This definition guarantees that 1 degree Celsius has the same temperature variation as 1 kelvin.
Digital thermo hygrometer with a thermocouple inside Anders Celsius initially proposed that the freezing point be 100 degrees Celsius, and the evaporation point 0 degrees Celsius. This was reversed in 1747, at the instigation of Linnaeus, or perhaps Daniel Ekström, the builder of most of the thermometers used by Celsius.
The Fahrenheit scale
Due to the low temperatures in northern European countries, Gabriel Fahrenheit had developed a previous scale to be able to measure the extremely low temperatures in these regions.
The conversion method for Fahrenheit consists of multiplying the value in Celsius by 1.8 and adding 32 to the result.
Similarly, to convert degree Fahrenheit to degree Celsius, subtract 32 and divide the result by 1.8.
The Celsius scale is used almost all over the world on a daily basis, although it was called centigrade until the late 1980s and early 1990s, mainly in weather forecasts on European radio and television networks such as the BBC, ITV, and RTÉ .
In the USA, Fahrenheit is the preferred scale for daily temperature measurements. It should be noted, however, that even these countries use Celsius or Kelvin in scientific applications.
Street thermometer. In newscasts and thermometers on major avenues in Brazil, they always refer to temperature on the Celsius scale, expressing it only with the degree symbol (°). Such a notation causes some confusion for North American visitors and is considered wrong by the SI (International System of Units), since the degree symbol after the numerical quantity without the letter C represents the angle symbol.
Scientific thermometers have mercury inside, and homemade ones usually contain alcohol (blue in color). The most modern and also precise are made by the union of two different metals, creating a thermocouple. Most modern thermometers and thermostats use a thermocouple.
Representation of the unit “degree Celsius”
Resolution Conmetro nº 12, of 10/12/1988, adopts the General Framework of Measurement Units and instructs INMETRO to propose the modifications that become necessary to this Framework, in order to resolve omitted cases, keep it updated and resolve doubts that may arise in the interpretation and application of legal units.
– Sub-item 3.5 of Annex A of this Resolution Conmetro deals with the spacing between number and symbol, and establishes that the spacing between number and symbol of the corresponding unit must meet the convenience of each case, for example:
a) In sentences of current texts, the space corresponding to one or half letter is normally given, but spacing should not be given when there is a possibility of fraud;
b) In table columns, it is possible to use different spacing between numbers and the symbols of the corresponding units.
– Conmetro Resolution 12/1988 is based on the parameters recommended by the International Bureau of Weights and Measures (BIPM), which regularly publishes a publication on the units of the International System of Units – SI.
– Subitem 5.3.3 of the 8th edition (2006) of the BIPM publication establishes conditions for writing the value of a quantity in the following terms:
a) The unit symbol must always be placed after the numerical value of the expression for a quantity, leaving a space between the numeric value and the unit symbol.
b) The only exceptions to the rule are the unit symbols for the degree, minute and second of the plane angle, °; ´; and ”, respectively, for which there is no space between the numeric value and the unit symbol.
c) It should be noted that, according to this rule, the symbol “° C” for the degree Celsius must be preceded by a space when expressing a temperature on the Celsius scale, as shown below:
Representation of the “Celsius grade” unit on computers
In Unicode, the degree symbol is U + 00B0 (°), while the respective HTML code is
°and the Alt + code is Alt + 0167.
Due to the similar appearance of this symbol with other symbols on the computer screen or in certain prints, such as the male ordinal indicator (º), there may be problems when searching for texts with these symbols. Therefore, for keyboards that do not differ between the degree and ordinal symbols, use:
degree Celsius: ALT + 0167 followed by the letter C.
male ordinal indicator: ALT + 167.
Temperature conversion table in degrees Celsius and Fahrenheit
Celsius into / for Fahrenheit: ( the C x 9) / 5) + 32
Fahrenheit into / for Celsius: ( the F – 32) x 5) / 9