There are parts of Chile that have a climate very similar to Ireland's. But other regions of the country are much more inhospitable, as Charles Darwin noted more than 150 years ago in The Voyage of the Beagle: "We rode on to Vallenar, which takes its name from Ballinagh (sic) in Ireland, the birthplace of the family of O'Higgins who under the Spanish government were presidents and generals in Chile. "That the surrounding country was most barren will be readily believed when it is known that a shower of rain had not fallen during the last 13 months. During this season of the year a heavy bank of clouds stretches over the ocean, and seldom rises above the wall of rocks above the coast."
Local ingenuity, however, has succeeded in devising novel ways of coping with these disadvantages of climate, in an area where the average annual rainfall is very close to zero. The answer has been found in the "heavy bank of clouds" that Darwin noticed hanging over the crests of nearby mountains. They provide an almost perpetual shroud of fog, which the locals call the camanchaca, and like any fog, the camanchaca contains vast quantities of water in the form of tiny droplets suspended in the air. It has long been noticed that shrubs and other types of vegetation are adept at exploiting such resources. They intercept the fog droplets with their foliage and deposit the water on the ground nearby - a process known as fog-drip. It works particularly well in California, where the giant redwoods near the coast filter the fog into its equivalent of gentle rain, and maintain a luxurious growth of vegetation where otherwise only the thorny, stunted growth of an arid region would survive.
Learning from the plants, scientists in Chile have developed a device called a "fogwater collector". It consists simply of nylon mesh stretched over a large wooden frame and mounted on the hilltop. The small fog droplets, blown against the mesh by the westerly winds from the Pacific, accumulate to form water drops, which eventually run down the mesh and into troughs; from there the water is collected in a reservoir for use whenever it is needed.
Surprisingly, a single fogwater collector can provide up to 50 gallons of water every day, so a small number of these devices is sufficient to supply the needs of an entire village, both for domestic and for irrigation purposes. And because the camanchaca is an almost permanent feature on many sections of the Andes in South America, the source of supply is almost infinite.