Fog collection

Fog collection refers to the collection of water from fog using large pieces of vertical canvas to make the fog-droplets flow down towards a trough below the canvas, known as a fog fence.

Through a process known as condensation, atmospheric water vapour from the air naturally condenses on cold surfaces into droplets of liquid water known as dew. The phenomenon is most observable on thin, flat, exposed objects including plant leaves and blades of grass. As the exposed surface cools by radiating its heat to the sky, atmospheric moisture condenses at a rate greater than that of which it can evaporate, resulting in the formation of water droplets.

The organized collection of dew or condensation through natural or assisted processes is an ancient practice, from the small-scale drinking of pools of condensation collected in plant stems (still practised today by survivalists), to large-scale natural irrigation without rain falling, such as in the Atacama and Namib desert. Several man-made devices such as antique stone piles in Ukraine, medieval "dew ponds" in southern England or volcanic stone covers on the fields of Lanzarote have all been thought to be possible dew-catching devices.

In the mid-1980s, the Meteorological Service of Canada (MSC) began constructing and deploying large fog collecting devices on Mount Sutton in Quebec. These simple tools consisted of a large piece of canvas (generally 12 m long and 4 m high) stretched between two 6 m wooden poles held up by guide wires, with a long trough underneath. Water would condense out of the fog onto the canvas, coalesce into droplets, and then slide down to drip off of the bottom of the canvas and into the collecting trough below.

The intent of the Canadian project was simply to use fog collection devices to study the constituents of the fog that they collected. However, their success sparked the interest of scientists in Chile's National Forest Corporation (CONAF) and Catholic University of Chile. With funding from the International Development Research Centre (IDRC), the MSC collaborated with the Chileans to begin testing different designs of collection facilities on El Tofo Mountain in northern Chile. Once perfected, approximately 50 of the systems were erected and used to irrigate seedlings on the hillside in an attempt at reforestation. Once vegetation became established, it should have begun collecting fog for itself, like the many cloud forests in South America, in order to flourish as a self-sustaining system.

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Wikipedia