Thursday, June 26, 2025

Hot and Cold on Threads



 

▪️Sharnbryn asks:  A question for people who know stuff about Fahrenheit:  

- Why is 0°F around -18°C? What happens at that temperature to make it notable enough to be 0°?

- 0°C is where water freezes, what happens at 0°F?

▪️jcgbigler responds:  Gabriel Fahrenheit invented the thermometer and was in the business of selling them to scientists for lab use. 0° was the coldest temperature he could create in his lab using salt & ice. 96° was body temperature, chosen as the other calibration point because he could divide it into increments of 1,2,3,4,6,8 or 12. Later, when he switched to water for calibration, 32° & 212° were chosen because they were backward compatible, and 212-32 = 180, which is divisible by 1,2,3,4,5,6,9,10,15 & 20. The calibration points don’t matter. What we (and scientists) care about is comparing one temperature with another. If it’s 40°F or 5°C (or 278 K) outside, I need a coat.  If it’s 90°F or 32°C (or 305 K) outside, I need to stop reading social media so I can spare myself the complaining.


▪️scottedson1 responds: The Fahrenheit scale is indefensible as a pure scientific matter but quite intuitive to humans. It is a good rough proxy for “percent hot” and the 0-100 do a good job of covering the overwhelming range of circumstances most people experience.  Temperatures outside of 0-100 F are, in fact, extreme for humans. So, it’s a bad scale for scientific discovery, but wonderful for describing the weather or temperature in a room to humans.


▪️sarevok8675309 responds with a graphic:


▪️gatomcwitchdesigns responds

- Fahrenheit is how humans feel. 

- Celsius is how water feels. 

- Kelvin is how the universe feels.


▪️davemtitle responds: 

Gabriel Fahrenheit used salt water and ice to get the coldest possible temp in his lab and marked his mercury column at that pint as zero. (It happens to be -18° C.). Then he  marked human body temp on the column as his 100° (he later recalibrated his scale to make body temp 96°)Spaces between were equally divided.  Anders Celsius chose freezing point of water as his zero and the boiling point as his 100.  It’s just a matter of reference points. 0° F just gets you very cold ice.


▪️Sclayworth responds: 

Easy guide to Celsius:

- 30 is warm

- 20 is nice

- 10 is cool 

- 0 is ice


▪️alfreedovara responds with a graphic:



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