Celsius to Kelvin temperature conversion is simple because both scales have the same size degree. There are 100 Kelvins between the boiling and freezing points of water and 100 Celsius degrees between the same two points. Fahrenheit to Celsius is a different matter. On the two thermometers to the left, notice that there are 180 Fahrenheit degrees between the boiling and freezing points of water. Conversion from Celsius to Fahrenheit must take into account the smaller degree size on the Fahrenheit scale.
Step 1 – Find the ratio of Fahrenheit degrees between the boiling and freezing points of water to Celsius degrees for the same two points.
* Fahrenheit degrees between the boiling and freezing points of water = 180
* Celsius degrees between the boiling and freezing points of water = 100
* Fahrenheit to Celsius ratio = 180 : 100 = 1.8 : 1
This means that for every 1.8 degrees that temperature changes on the Fahrenheit scale, temperature will change 1 degree on the Celsius scale. Thus the ratio of Fº to Cº is 1.8 : 1
Anders Celsius should be recognized as the first to perform and publish careful experiments aiming at the definition of an international temperature scale on scientific grounds. In his Swedish paper “Observations of two persistent degrees on a thermometer” he reports on experiments to check that the freezing point is independent of latitude (and also of atmospheric pressure!). He determined the dependence of the boiling of water with atmospheric pressure (in excellent agreement with modern data). He further gave a rule for the determination of the boiling point if the barometric pressure deviates from a certain standard pressure.
Maximum and minimum thermometers are universally used in weather-reporting stations. The maximum thermometer includes a magnet that fits tightly inside a capillary tube and is moved up the tube by the rising mercury. When the temperature falls, the magnet remains in position, thus enabling the maximum temperature to be recorded.