Article Summary: 'Twinkle, twinkle, little laser'

Article Title: ‘Twinkle, Twinkle, little laser’
Publishing Date: Jan 21st 2009
Published on: Economist.com
URL: http://www.economist.com/research/articlesbysubject/displaystory.cfm?subjectid=348924&story_id=12966262

Water is a precious resource and a scarce one in certain parts of the world. One reason for this is that farmers do not know when and how often to water their crops and therefore do it instinctively or at set times. Automatic sprinklers make the watering itself easier, yet the problem is the amount of water that is being wasted, which is a severe problem not only for poorer countries.
Previous measures to curb water usage in drought-prone areas of the world, such as California, have not had a great effect; rising water bills and limiting the amount of water that can be used are two of them. However, a new method has been developed by Dr. Kleissel and his colleagues of the University of California, using an apparatus called a ‘scintillometer’. With the use of lasers, the amount of moisture above a crop can be detected, which allows the farmer to determine if and how much the crop needs to be watered. This is done by computing the amount the laser beam twinkles as it passes across a field towards the telescope. The more the laser beam twinkles, the more water is evaporating from the field, meaning that the plants need to be watered. This method is derived from the fact that stars appear to twinkle since the air currents caused by evaporating water make their light shimmer as it passes through the earth’s atmosphere.
This technology has found other applications too, such as measuring conditions above airport runways. This particular innovation costs between ¼ and ½ a million, meaning it is not readily accessible to the average farmer. Therefore it is currently only a method applicable to large farmers that may or may not be located in drought prone areas.