The influence of weather variability on evaporation leeward of A medium porous barrier

Abstract

AbstractBlack porous disc atmometers were used to measure daily evaporation (E) at a distance of 4H (where H is barrier height) leeward of a medium porous hedge and in the open. The modification of E at the sheltered position was defined, in relative terms, as the percentage of the sheltered E to that in the open (relative E) and in absolute terms as the difference between the open and sheltered E totals. Although relative E was found to vary as a linear function of the relative wind (RW), E differences varied also with the meteorological conditions influencing the ‘evaporative climate’, identified here by the weather parameters: cloud cover, relative humidity and wind speed. For a particular value of relative E, the E differences were greatest on days with no cloud, low humidity and moderate wind speed and least on cloudy, humid days with low wind speed.