Thanks for the thread! I think the whole air-well-idea is very interesting! :)
A lot of informations about different approaches can be found on the web.

How about a recipient with a hour-glass shape? The bottom half in the ground or insulated so the collected water is not heated again and the top half solar-heated. The question remains how to create air circulation.

I would try having a large bottle and a smaller bottle. Fit the small bottle inside the large one. Fill almost all of large bottle with water. Water cools slower than air so it will increase the rate of condensation. A metal cone could also be added to the smaller bottle to speed condensation. My idea was to have it put in a car and have the a/c run over the external of the reservoir to cool the water and then have it stored in the car for drinking water. If you did that it would solve bringing a water bottle in your car but then it getting warm.

http://www.plastic-mesh.coma good idea

See the Wikipedia article:

I think existing airwells work by two principles. One type takes advantage of seasonal temperature differences; summer vrs winter. This type works by cycling the surface air thru pipes or rooms underground. The other "standard" type takes advantage of the difference in day/night temperatures. The salad dressing bottle appears to be functioning as this type of airwell. Dew on the windshield and "bridges may be icy" are examples of this type of air well. I suspect that "dew ponds" work on this principle. Dew ponds have a long history, perhaps dating back to the Neolithic. In "Naturalist on the Thames" the author described a dew pond that produced upwards of five acre-feet of water a year... unfortunately he didn't give the dimensions of the pond. Russell's "improved dew reservoir" is 900 square-feet and five feet deep; deep enough that it may work on the summer/winter temperature differential instead of the day/night temperature differential. Either way, it only produces a tenth the water recorded by Cornish in "Naturalist on the Thames".

I came across this a few weeks ago....

Water Cone

Compact and lightweight - I think they can be stacked and I'll bet you can get higher efficiency if you insulate the bottom pan :) If I were to make one, this is the design I'd try to replicate :P

1-1.7L per 24 hours. That's 4+ to 7+ glasses per day :)

where i live it is often very foggy sometimes in the morning. Perhaps if you strechted a thin peice of cloth between two poles with something similar to a roof gutter benaeth it. The water in the air would drip down the cloth into the gutter. You could put a bunch of these in series and get a considerable amount of water...... maybe i will try this.

Try putting some aluminum foil around the bottom of your vinegar bottle, to protect the accumulating water from getting heated up and evaporated again by the sun. What kind of material is the windowsill made of? I assume a marble windowsill would keep the bottle cooler than a wooden one, for example.