The dictionary of the Royal Spanish Academy (RAE ) indicates that the adjective centigrade it is used with reference to that linked to the centigrade scale . This scale, also called Celsius , it has the melting point of ice as value 0 and the boiling point of water as value 100 , always at normal pressure.
A degree centigrade or Celsius grade is a unity which is used in this type of scales . His symbol is ° C and is specifically used as temperature unit (the physical magnitude that reveals the level of heat).
As you can see, the notion of centigrade is associated with Anders Celsius , a Swedish scientist who was born in 1701 and he died in 1744 . Celsius He proposed a centigrade temperature scale in which, as the heat increased, the degrees dropped. Simultaneously, when the heat was reduced, the degrees increased. Years later, Carlos von Linnaeus and Jean-Pierre Christin they started from the ideas developed by Celsius to create a similar scale though inverted (the degrees increase when the temperature rises and decrease when it falls).
At present, this centigrade scale whose degrees increase as the temperature ups is used in numerous countries to indicate the level of heat. That is why it is usual to read or listen that there is a temperature of 5 degrees Celsius or of 28 degrees Celsius , for example. According to the scale in question, the 28 degrees Celsius they refer to a temperature that registers a higher heat than the 5 degrees Celsius .
It is important not to confuse this concept with that of centesimal grade , a unit of measure that is used as an alternative to radian and sexagesimal degree to work with flat angles. It is also known as gon, gonio and gradián. his value It is explained as the central angle with a length equivalent to 1/400 of a given circumference. While gon is its international symbol, a letter is usually used g lowercase at the end of the figure located in the superscript position.
Until 1948, the centesimal degree was also called the centigrade degree. However, the authorities of the International System of Units they considered that it was necessary to find an alternative to reduce the likelihood of confusion and that is why they officially adopted the denomination Celsius grade.
Regarding the indiscriminate use of the terms centigrade and Celsius it is necessary to mention that it is not about synonyms in all cases, since there is at least another centigrade scale with which confusion could be generated, that of Kelvin . The Kelvin scale is also based on a division in one hundred equal parts for the measurement of the boiling and freezing points of the Water distilled
One of the differences between the Kelvin and the Celsius degree is that the latter represents an accessory unit, that is, it is not the basic of the system , as it happens with the first. Today the definition of the degree Celsius starts from Kelvin and is expressed by means of the following equation: t(° C) = T(K) - 273.15 . Any temperature range has the same value in degrees Celsius and Kelvins.
Therefore, we know that these two units can be mentioned as degrees Celsius by using as a reference a division into one hundred parts of the same magnitude. There is on the other hand the Fahrenheit grade , a scale proposed in the year 1724 by the physicist and engineer Daniel Gabriel Fahrenheit for the measurement of the temperature, according to which the water freezes at 32 degrees and boils upon reaching 212.
For reference, let's look at the conversion between these three units: the melting point of water at 1 atm of pressure is 0 ° C, 32 ° F or 273.15 K; the boil at 100 ° C, 212 ° F or 373.15 K.