How to Calculate Air Temperature

Temperature units are all about the base temperature and growth algorithm.

You may be surprised to learn just how many different units of temperature measure there are. Beyond the common Fahrenheit and Celsius measurements you'll find Kelvin, Rankin, Reamur, and Rømer (the precursor to Fahrenheit). You're unlikely to encounter the Planck, thermodynamic beta, or accumulated thermal unit scales outside of a physics laboratory, but you may be closer than you think to a working model of the gas mark scale.

Instructions

1. Note your degrees in Fahrenheit; since this is the most common unit of measure in the United States, we'll start from there. Use 80 degrees Fahrenheit (80F) as a base.

2. Convert to degrees Celsius by subtracting 32 and multiplying by 0.555. In our 80F example, this comes out to 26.4 degrees Celsius.

3. Convert Fahrenheit to Kelvin by adding 459.67 and multiplying by 0.555. Our 80F example comes out to 299.145 degrees Kelvin. Kelvin is a vital measurement in physics and chemistry since it uses absolute zero as its calibration point and Celsius as its growth algorithm. Absolute zero is the temperature at which all thermal motion ceases and is the coldest that anything in the universe can get.

4. Convert to Rankine by adding 459.67 degrees; our 80F example comes out to 539.67 Rankine. You can think of Rankine as Fahrenheit referenced to absolute zero, and Kelvin as Celsius referenced to absolute zero. Although Kelvin has largely superseded Rankine in most fields, this somewhat archaic measurement is still used in some North American engineering fields.

5. Convert Celsius to Reaumur by multiplying the degrees Celsius by 0.80. Convert Fahrenheit to Reaumur by subtracting 32 and multiplying by 0.444. Convert Kelvin by subtracting 27.15 and multiplying by 0.80, and convert Rankine to Reaumur by subtracting 491.67 and multiplying by 0.444. The Reaumur scale was quite popular in 19th-century Europe but is no longer in use today.

6. Convert to the gas mark scale if you want an estimate of your propane stove's flame temperature and the concurrent temperature of the pot or pan on top of it. The gas mark scale uses eleven marks. The bottommost 1/4 mark equals 225 degrees Fahrenheit, and the 1/2 mark equals 250F. The 1 mark equals 275F degrees Fahrenheit, and the temperature rises by 25F degrees for each subsequent mark; the 2 mark equals 300F, the 3 mark equals 325F, and on to the 9 mark at 475 degrees Fahrenheit. Cookbooks often use the gas mark's descriptive equivalent, where 1 = low, 4 = medium, 6 = high, and 9 = very high.

References

• University of Illinois: Units of Temperature
• Converte Me: Unit Conversion Factors
• Practically Edible: Oven Temperatures
• Zapatopi: On an Absolute Thermometric Scale - by William Thomson