h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Anyone out there got any experience of making tea at high altitude? My Mum (a quintessentially English tea drinker) says that you can't make a decent cup of tea up a mountain. The reason being that the water boils at less than 100 degrees Centigrade, therefore your tea will taste crap.
Dying to know.
Migs and Leo in Edinburgh

Alas, 'tis true.

I'm an Englishman who has recently moved to Colorado Springs, Colorado, USA - altitude 6,200 feet.

I don't know at what temperature (anyone?) water boils here, but you can't get a scalding hot cup of tea.

My 2 cents (pence) worth!

I would have thought it difficult to make a decent cup of tea up a mountain, for the simple reason that I cannot think of anybody who would take a teapot with them!!
The physics is right though. The boiling point is lower the higher you go up.

Isn't the point that you BOIL the water? I don't think it matters at what temperature it boils, as long as it boils. The process should be the same.
Note : I'm Dutch. I don't drink tea. Hate the stuff. Gimme a good strong cup of coffee and I'm happy.

Yes you do boil the water, but the problem is that it boils at less than 100 degrees C up a mountain, so is less hot.

how do i add my own text to that forum i wonder?

oh i see

silly me!ok how we make tea in kurdistan?actually you ve got two pots:a big one with hot water and a smaller pot on top of it
in the smaller pot is the actual tea which is very very strong.so what you do is you put the very strong concentrate in a little teaglass
and than add the water, right?now that tastes very disgusting unless you dont put lots of sugar in it.my mother(and many others) for example she puts
a sugarcube in her mouth somewhere under her toung and let it disolve with every bit of tea she drinks which is very difficult and needs a lot of
practise and its very unhealthy because of your teath.in kurdistan only kids put milk in their tea.even that i brought up with this kind of tea-culture
i cant stand it anymore i like the english way of having a cup of tea but without milk cause i am not a kid anymore.

I suppose that if you want to have water boiling at a reasonable temperature of 100 degrees (or even more!) when you're at high
altitude, you need to make or purchase some sort of pressure kettle. Trouble is, once you open it, it would probably all go to vapour.
Maybe you need a pressure mug, too.

I know! So the actual question is, are the 'pollutants' in the water (For example the thin film of stuff you get on your tea when you don't boil it)being broken down at lower temperatures also? That's the whole point of boiling the water in the first place I presume.

I never drink tea but maybe I can help you out.
Suppose that the problem with tea in the mountains is that when you boil water the temperature is lower (so the question of good tea should not be to boil or not to boil, but rather to have a water temperature that is high enough).
The reason that water boils at a lower temperature on altitude is the difference in air presure.
So the solution is simple increase the air presure. How to do this ?
Well think of a kitchen utility that you can buy - of which not being natively speaking english, I don't know the name - that allows you to cook faster. (If I translate leterally it would be fast cooking pot - for dutch speaking people : snelkookpan).
Now the principle of such a pot is exactly to seal of the pot of air, so that it builds up presure inside and the water cooks at a higher temperature, which allows you to have your vegetables ready faster.
If you have ever seen someone using such a pot you know that after cooking you have to open it in a special way, and the steam escapes.
This is, I think exactly what you need. Use such a pot in the mountains to boil your water and I see no reason why you wouldn't be able to make the same tea as at sea level.

I seem to have missed a reply of someone else so the name is "presure kettle" and I don't seem to be the only one to have though of it.

You have to get the water temperature up to at least 96 degrees C otherwise the tea will not infuse properly. The higher up you go the lower the boiling point of the water. Too high and the tea will not infuse.

No no no no no, you are not boiling the water to get rid of the pollutants, you are boiling it to allow the tea to infuse the water properly, The hotter the water the better the flavour dissipates... Mmmmm, prefer breakfast tea to Earl grey myself but the theory is the same... If you must insist (or are forced) to make tea in the cup, you must pour the boiling water directly onto the teabag in the same way as you would in the pot.. then leave it - don't stir. mmmm! top.

Okay okay fine. So we've all gone up this mountain, we've got our pressure kettles, our pressure mugs, our pressure teapots, our calor gaz thingy, a carton of milk, and are ready to make tea. Proper tea. Real tea.
We find a mountain spring. Purest freshest mountain springwater. Uncontaminated. Just bubbling out of a crack in the rocks. No sheep dropping nearby. It must be good.
Fill the pressure kettle. Start the gaz. Get it going. Eventually it emits a steam jet indicating it is ready (I've seen one on telly do this - so it must be true). Open it (which, by the way, terrifies me) and pour some into the pot to warm it. Sloosh it around and tip it out. Now we are close. Now is nearly the time. Silence in the mountains as the ritual nears it's peak (sic)(unintended).
Oh crap. Who forgot the tea?

Nope - won't work. The moment you take the top off the pressure cooker the water above boiling point (somewhat less than
100 degrees as discussed earlier) will vapourise. The only sensible way to do it is to carry a pressurisation chamber up the
mountain with you. The entire boiling and brewing process can then take place within the chamber and the perfect cup of tea
achieved.

Of course, this also allows for the possibility of adjusting the pressure up (within reason otherwise you'd have to evolve into an
entirely different life form capable of withstanding 5000psi but probably incapable of drinking Tea) and experimenting with the
effect on flavour.

So, anybody else interested in this vital research project ? All we need, I reckon, is a couple of million from the EU Cultural
Integrity fund and bob's your father's half brother (on his mothers side).

The water needs to be as close to 100'C as you can get in order to dissolve the tea properly.

If the water's boiling at 80'C (i.e. below one atmosphere's pressure) then dissolution will not take place.

The best tea I've had at altitude (2000m) was chai-style tea (or that's what the mate who made it called it) Add tea, sugar, milk (powdered) and cardamom pods to boiling water, and simmer until ready.

OK, so how bad is this problem really??? So far everyone has managed to avoid the real issue here: What is the boiling point of water as a function of altitude? Well, I did it. I went and dragged out my old (1960) copy of Kohlrausch: Praktische Physik, and found that:

a) the average pressure in Torr (roughly = mm Hg) is
p=760*(1-(0,0065*h*/288))^5,255
with the hight h in meters

and

b) the boiling point of water in deg. C is
Tp =100+0,036858*(p-760)-0,00002015*(p-760)^2
+0,0000000162*(p-760)^3
with the pressure p in Torr

What this boils down to (sorry ! ) is the following table:

Alt.km Alt,ft Pres,Torr Water BP, dec. C
------------------------------------------
0 0 760 100,0
1 3281 674 96,7
2 6562 596 93,4
3 9843 526 90,1
4 13123 462 86,8
5 16404 405 83,7
6 19685 354 80,6
7 22966 308 77,7
8 26247 267 75,0
9 29528 230 72,4
10 32808 198 70,1
11 36089 170 67,9
--------------------------------------------

So, at 2000 meters altitude the boiling point is approx. 93.4 dec C.
Now, how does this affect the tea taste???

If anyone really would like to see the Excel spreadsheet used to calculate this, I've thoughtfully uploaded it to:
http://home.worldonline.dk/~gjensen/boil.xls

Has anyone here tried making tea while in a diver's decompression chamber???? (not me, anyway ! )

> Now, how does this affect the tea taste???

At 2000m, it doesn't taste as good to me, but I do like relatively strong tea. I suppose using powdered milk doesn't help, but even with fresh milk, there's still *something* missing. Pre-heating an insulated mug to make the tea in does help a little, but not enough. It's not so much the strength of the tea, it's more that parts of the 'proper' flavour are missing. (But then, I grew up drinking tea brewed at 100 deg.C, so my 'proper' may be different to other peoples')
It's a little like the difference between fresh and instant coffees, or between a cup of fresh tea and one reheated in a microwave (Ugggh).
Still, at the altitudes I spend time at, it's nowhere NEAR as bad as...

... Instant Tea.

*Runs off to wash mouth out*