[kdlynn (OP)]

according to my family in colorado, the water boils faster in higher altitudes but it is not as hot as it should be. why would altitude cause this?

[another_someone]

Simple answer - air pressure.

The opposite happens when to boil water in a pressure cooker, as when you heat water in a pressure cooker, as the temperature builds up, so the pressure builds up in the cooker, so it delays the boiling of water until you get to a higher temperature.

Because water expands as steam (there are other factors as well, but that is the simplest to visualise), so the more pressure you apply to is, the more difficult it is to convert to steam.  If you place water in a vacuum, it will evaporate immediately (it will go straight from ice to steam, and will not stay in liquid form).

So, as you move up in altitude, air pressure becomes less, and water boils at a noticeably lower temperature.

[kdlynn (OP)]

wow. thanks

[kdlynn (OP)]

wait. hold on. so let's say that we somehow started a fire in the ocean. how hot do you think it would have to be to boil water at the bottom of the ocean?

[kdlynn (OP)]

or more probably, very far down under ground

[another_someone]

Underground is easy - just add the extra air pressure, and increase the boiling point accordingly.

The bottom of the ocean is going to get very complicated.  Firstly, you are dealing with salt water, and secondly, you might get local boiling, but it would not reach the surface unless you could warm up the water column above you.  There are submarine volcanoes that are several hundred degrees Celsius that never get to boil the oceans.  There are even organisms that are living in water well over 100 Celsius (near these submarine volcanoes), but because the water is not boiling, they can adapt to the heat.

[kdlynn (OP)]

does any of this effect the water freezing?

[another_someone]

does any of this effect the water freezing?

Yes, but the relationship is quite complex in that regard.

We had a thread on this a little while back - will have to look it up.

Most substances will shrink when they freeze, so compressing the substance will raise its freezing point.  Water is peculiar in that it expands when it freezes, so you go through different states as you compress it around its freezing point.

http://www.thenakedscientists.com/forum/index.php?topic=7243.msg75519#msg75519