I was recently on a trip at 5,000 feet with a bunch of people I don't know well, all of whom swore that water "takes longer to boil" at higher altitudes. I'm pretty sure they were confusing boiling time with cooking time (which is longer for boiled foods at altitude because the boiling point of water is lower there).

My offered suggestions (stronger stoves at home, weaker stoves in vacation rentals; more leisure to watch the pot leading to perception of longer boiling) were rejected out of hand.

Boiling time should be shorter at altitude because the boiling point is lower, right? But is there any sense in which my travel buddies might be right? Is there any effect of altitude on the rate of heating of the water?

  • $\begingroup$ If you use a fuel cooker you may have small loss of heating efficiency due to less oxygen to burn. With electric you should notice no change in heating with perhaps slight changes in when the dissolved gases leave the water (earlier that is) and slightly lower boiling temperature. Ask your friends what they base their sworn statements on. $\endgroup$ – KalleMP Jan 21 '18 at 13:34

You are right in your explanation. It doesn't take longer to boil water. Rather it takes longer to cook food using water because less heat is transferred to the ingeredients by radiation or conduction. About the "rate of heating" of water, the higher you go the shorter it takes to heat water. Hence, the rate of reaching the temperature of boiling increases. How do you define "rate of heating"? Do you mean rate of energy transfer to the ingredients?

  • $\begingroup$ I guess I was talking about the specific heat of water -- does it change with altitude? $\endgroup$ – user2392070 Sep 20 '16 at 20:03
  • $\begingroup$ I think there's no better way to explain it than this answer here. Please follow the link physics.stackexchange.com/questions/100044/… $\endgroup$ – Sad_lab_rat Sep 21 '16 at 14:03

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