I was watching a recording of "What the Ancients Knew: India", and there is a part that says (paraphrased):

" Rows of shallow pots filled with water were covered with straw and exposed to a draft. The evaporation chilled the water, and could produce small quantities of ice"

Anyone have any straw to test? On the show, it dropped a few degrees.

I don't know about ice, but that sounds a lot like a simple swamp cooler, to "air-condition" a room. As the air travels through the damp straw, it increases the humidity in the area and makes the temperature feel cooler.

Cooling by evaporation does work. The energy to evaporate the water is taken from the surrounding air. A draft will speed up the evaporation and the water temperature drops. There is an equilibrium where the heat flow to the water equals the energy to evaporate water at this temperature. However I doubt that the effect is powerful enough to generate ice while the air has room temperature.

If you have a solar cooker try this:

Set it out After the sun has gone down and point it straight up. It will work in reverse and you can have frozen water even while the room temperature is well above freezing!

It's legit. I think I've posted another site's info on this. Here's a similar article from the BBC: http://www.bbc.co.uk/dna/h2g2/A2116766

I'm not sure it will make ice, but the method described is a bit different (using shallow pots filled with water). Anyway, I've thought about getting the local potter to build me one. <img src="/images/graemlins/smile.gif" alt="" />

Our pioneers would make a simple cooler by hanging a wooden box that had no top or bottom on its side in the sun. They would set a bucket of water on the top and drape fabric over the whole thing. The fabric would be weighted to keep part of in the water, and the constantly-damp fabric would hang outside the food in the box, keeping it cool.

But it wouldn't make ice.

Sue

Is this the same concept Myth Busters busted with the cold beer with fire trick.

The Romans had a trick to produce ice in the desert. It relys upon the very low (i.e. below freezing) temperature's you can get at night in a desert enviroment. What you do is: 1) Dig a deep pit. 6' or more. Once you get so far down the temperature stablises at around 50° F or so. 2) line your pit with a generious amount of straw. 3) At dusk put your container of water in the straw, leaving the top open. 4) Leave alone untill just before dawn. 5) Just before dawn, cover it over, with plenty of straw. More the better. 6) cover the top of the pit with something very reflective ( the Romans used a polished shield or two.) Repeat over one, two or three nights untill ice forms.

I have no idea, as I don't have TV. I read about it in a pioneer's diary. It's quite possible that our current idea of cold isn't quite the same as that of someone in the 1850's living on the plains in summer.

Sue

Lazermonkey, no, it's not, this is straightforward evaperative cooling. And;
Sue, yeah, I would imagine it is QUITE different, the box, rag, and tub of water setup will give you an enclosed area that's 5-20 degrees cooler than the outside temp., depending on shade, or lack there of, amount of breeze blowing, size of the container, etc. It's not a refrigerator, but when it's 90 degrees+, you'd be surprised what a 15 degree temperature change will do for butter, cheese, your drinking water, or a beer, just to name a few <img src="/images/graemlins/wink.gif" alt="" />.

Troy