Degrees Gregable

Jun 26, 2014

While recently travelling in Europe, I repeatedly needed to convert between published temperatures in Celsius and familiar numbers in Fahrenheit. It got me thinking a bit about temperature scales.

With distance, the multipliers between units at different scale makes a strong argument for metric units (ie: 100cm/m, 1,000m/km, rather than 5,280ft/mi). Temperature doesn't have this problem as there is only one unit on each scale (degrees). One does not count centidegrees. There is no argument to be made for preferring one scale over another except based on which memorable numbers correspond to real-world values.

Most everyone knows that Celsius is designed around 0° and 100° lining up to water freezing and boiling points respectively. However this definition isn't sufficient for lab purposes. Water freezes and boils at different temperatures depending on pressure and impurities. The technical definition is at one standard atmosphere of Vienna Standard Mean Ocean Water. Then again, how often do most people need to measure the temperature of ice and steam reliably? Not I.

Far fewer people know that 0° and 100° in Fahrenheit also correspond to specific real-world values. 0°F corresponds to a temperature where a brine is made of equal parts ice, water, and ammonium chloride. Such a brine, interestingly, is a frigorific mixture, meaning that it stabilizes to a specific temperature regardless of the temperature that each component started at. Thus, it makes for a really nice laboratory-stable definition of a temperature. Similarly, 100°F was initially set at "blood heat" temperature, or the human body temperature. While not super precise, it was a fairly stable value. As good as anything in the early 1700s.

Today, we can produce very specific temperatures in very controlled environments. We hardly need to use water, ammonium chloride, or blood as the master keys to our temperature scales. Nor do we need to fret about calibrating our thermometers that often. That feature of a temperature scale is simply no longer the most important one. How could we improve temperature scales if we were to reinvent them today?

I present one possible suggestion. Most people primarily use temperature for measuring ambient air temperature for purposes of assessing comfort level. Why not build a temperature scale around the notion of comfortable air temperature?

0° in this scale then can be centered at a very comfortable room temperature. Something around the area of 70°F / 20°C.

-100° and +100° could then be at the limits of human comfort ranges. Something around the area of 40°F/5°C and 100°F/38°C respectively.

New °C °F
100° 38° 100°
50° 29.6° 85°
21.2° 70°
-50° 12.8° 55°
-100° 4.4° 40°

Now, the phrase "tomorrow it will be twice as cold" can be represented reasonably in mathematical terms - simply double the current temperature and you'll know tomorrow's temperature, a feat that didn't always work so well with older temperature scales.

We need a new symbol for this new scale, so as not to confuse anyone (more than necessary). I propose °G, pronounced "degrees Gregable".