Fischers in Peru

On cuppas at altitude

18 Dec 2022

Well, I got to wondering a bit about altitude, living as we do at 2,300 metres here in Arequipa (which is pretty-much the height of Mt. Kosciuszko).  We all know that water boils at 100 deg. C at sea level -- but what about at 2,300 metres?  Or at 4,200 metres (Tisco, here's looking at you)?

[In the old days, boys and girls, for question like this the avid student would reach for the Encyclopaedia Britannica, which most households had courtesy of those door-to-door salesmen.  But like a lot of things, the internet kind of wrecked that business model, so now you just use your smartphone instead.]

So here's the deal: the boiling point of water here in Arequipa works out at about 93 deg. C, which probably explains why our electric kettle is so reluctant to turn off automatically.  And it also helps explain why we don't seem to burn our lips so often with a fresh cup of tea.  Want to find out the boiling point of water at your altitude?  Look it up on this graph here.

What about oxygen availability?  We've all seen the doccos: if you want to make it to the top of Everest (8849 metres), then oxygen cylinders are an excellent idea.  So here in Arequipa?  Another handy graph settles the question: at sea level there is 20.9% oxygen available.  Here in Arequipa that's down to 15%.  So I guess that means that with each lungful we're getting 25% less oxygen here than we would in Perth.  No wonder we found ourselves gasping (more than usual) while climbing stairways!

Ah, the mighty smartphone.  Makes even me feel smart.  Although I do feel a bit nostalgic for the old Encyclopaedia Britannica...