Temperature Scales
Thermocouples and Sensors
October 9, 2022Sound Level
October 9, 2022
Absolute Zero (-273 °C) is the temperature at which all molecules stop moving. It is not, as some have cruelly suggested, calibrated against a Republicans compassion, a salesman conscience or the National Party’s polling numbers!
I’ve been thinking about temperature, because after a relatively balmy, autumnal May, June’s winter has bitten hard. As I write this (June 6) I look at the temperature graph for yesterday from my logger in the back yard, and note that in Canterbury we reached a high of 8.6 °C at 3pm so never broke double digits.
I hate to be an unconventional, but I think Fahrenheit may be the better temperature scale for weather measurements. In the English language the word ‘zero’ is a synonym for the word ‘nothing’. So, we give 0 °C more meaning than it perhaps deserves. 0 °C clearly doesn’t mean that there is no-temperature; it just means it’s cold.
When I came out to my car this morning, there was a thick layer of frost and it was -2.8 °C. But what does that mean. Listening to a US weather forecast, they’d say, “it’s cold; in the low 20’s” and that makes some sense cognitively.
Mr Celsius based his zero-point on freezing water. Mr Fahrenheit based his zero point on the coldest temperature he could achieve in his laboratory (-18 °C).
Actually, fun fact. Celsius actually had his scale reversed initially. 100 °C was freezing water and 0 °C was boiling water. It was changed later and renamed Centigrade.
So we have 3 main scales: Fahrenheit, Celsius and Kelvin. Each referencing a zero point; Fahrenheit's brine solution, frozen water and absolute zero.
You may have noticed that light bulbs publish their ‘colour’ as temperature in degrees Kelvin. This is because they describe the colour produced by a perfect black body at that temperature. In the Homershams office we have some fluorescent lights that are 'Cool White' (3000 °K) and some Daylight (5000 °K). Higher temperature bulbs are far less forgiving to those of us over 50. Candlelight is most flattering because it’s low temperature (2700 °K) makes one looking redder and healthier.
