Celsius, capitalization

Lowercase letters are also used for units derived from surnames when they appear in spelled-out form and do not follow a number. The abbreviated form, used as a unit after a number, is capitalized. Celsius and Fahrenheit are always capitalized because they refer to temperature scales (not actual units). 

Celsius and Fahrenheit are always capitalized. They are not themselves units they are the names of temperature scales. 

The symbols for Celsius temperature and Kelvin temperature are lowercase t and capital T, respectively. Be careful to use the proper... 

C can be regarded as the absolute zero of temperature. Since there cannot be less than zero volume, there can be no temperature colder than 273 °C. The temperature scale that has been devised using this fact is called the Kelvin, or absolute, temperature scale. A comparison of the Kelvin scale and the Celsius scale is shown in Figure 9-1. It is seen that any temperature in degrees Celsius may be converted to Kelvins by adding 273°. It is customary to use capital T to represent Kelvin temperatures and small t to represent Celsius temperatures. 

Another temperature scale, used in Canada and Europe and in the physical and life sciences in most countries, is the Celsius scale. In keeping with the metric system, which is based on powers of 10, the freezing and boiling points of water on the Celsius scale are assigned as 0 °C and 100. °C, respectively. On both the Fahrenheit and the Celsius scales, the unit of temperature is called a degree, and the symbol for it is followed by the capital letter representing the scale on which the units are measured °C or °F. 

In the metric system the calorie is defined as the amount of energy (heat) required to raise the temperature of one gram of water by one Celsius degree. The "calorie" with which you are probably familiar is used to measure the energy content of food and is actually a kilocalorie (1000 calories), written with a capital C (Calorie) to distinguish it from the calorie used in chemistry. The joule (an SI unit) can be most conveniently defined in terms of the calorie ... 

The convention followed in this book is that aU physical quantities are in italic type, while symbols for units are in normal type, so for instance we might say that the force F is 15 N the viscosity rj is 10 Pa.s and the shear rate y is 0.1 s-i=. S5rmbols for unit names derived from proper names begin with a capital letter but the tmit names themselves are not capitalised, i.e. N for newton, P for pascal and Hz for hertz. The unit name should not be followed by a full stop, and plurals of unit symbols should not be followed by an s, e.g. 3 kg but not 3 kg. or 3 kgs. If we are quoting temperature T in absolute units, i.e. kelvin, then no ° s)mibol is needed, e.g. 200 K. However if you are quoting the temperature in Celsius or similar, you should put °C. 

Energy expenditure is measured by the output of heat from the body (section 5.1). The unit of heat used in the early studies was the calorie — the amount of heat required to raise the temperature of 1 gram of water by 1 degree Celsius. The calorie is still used to some extent in nutrition in biological systems the kilocalorie, kcal (sometimes written as Calorie with a capital C) is used. One kilocalorie is 1000 calories (10 cal), and hence the amount of heat required to raise the temperature of 1 kg of water through 1 degree Celsius. 

The solution to this problem lead to the creation of absolute temperature scales, ones on which 0° truly means the absence of any heat. The first absolute temperature scale was the Kelvin scale, named for the British physicist William Thomson (1824-1907), who went by the title Lord Kelvin. It is perhaps a technical point, but absolute temperature scales do not use the degree symbol hence, a temperature on the Kelvin scale is expressed in kelvins (k), not degrees Kelvin, and not capitalized. The size of a degree on the Kelvin scale is the same as the size of a degree on the Celsius scale, so the conversion between the two scales is relatively simple ... 

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