Temperature is the measurement of hot and cold. What is cold and what is hot ? For us, cold means when the temperature is lower than the external body temperature. This is what we feel, if the temperature is lower than external body temperature we think it is cold, if the temperature is higher than that, we say that it is hot.
Why ? Because this is what out body tells us. But, can we say that a cup of tea is hot at 40 degrees celsius ? No, usualy we say that it is hot when it boils. This happens because we think in different ways when thinking about temperature, depending in the psyhical object that we are talking about.
This is the reason that we have to deal with different temperature scales, because people thought it is better to use different temperature scales for different psyhical phenomens.
The main temperature scales are Fahrenheit, celsius, kelvin and rankine. The celsius scale is based on water. The 0 point on celsius scale is the point when water change it's state from liquid to ice at a normal pressure, and 100 degrees celsius is the point when water changes it's state from liquid to gas. Celsius scale was made from Kelvin scale, but adapted to have those 2 key points at 0 and 100 degrees.
To convert from Kelvin to Celsius you have to substract 273. The reverse is to add 273. The conversion from fahrenheit to celsius is more complicated. The formula for this transformation is: Fahrenheit = Celsius * 9 / 5 + 32 . It looks complicated and you may thing that you will never be able to do it without a calculator, but you can, let me explain you the easy way. You have the temperature in Celsius, double it and then add 32. It is not exact, but 9/5 is 1.8 which is close to 2. For exact conversion, after you double the celsius value you can substract 10 percent from the value, which is not very complicated. For example, take 28 degrees, double it you get 56, 10% from 56 is 5.6, very simple , you have 50.4, and then add 32 which will make it 82.4.
If you want a quick conversion and you are in front of a computer with internet conectior or you are using a mobile device, use an online temperature converter: Celsius to fahrenheit
The rankin scale is very simple to convert to, get your fahrenheit temperature and add 459.6 .
Each scale is good when doing math in different situations, that is why we need different scales. There are many other scales but they are not so important, they are used for math.
