The Fogfinder Project.

The sensor is part of a larger system, known as Fogfinder, which was developed by Dr. Richard LeBoeuf in collaboration with Jorge Gomez and Juan Pablo Vargas – CEO Entelequia SPA – for Universidad de los Andes in Santiago, Chile.

http://www.digi.com/blog/examples-guides/fogfinder-relies-on-arduino-and-digi-xbee-to-tap-into-new-water-source/