Abstract
Local modifications of air flow caused by the construction of the Arenal Reservoir in Costa Rica were investigated. From the analysis of data recorded at a station near the downwind side of the reservoir for the years 1972–75 before and the years 1980–83 after the formation of the reservoir, it was found that the direction of the prevailing wind was always from the northeast (corresponding to the northeast trades), whereas the magnitude was appreciably increased for the period after the formation of the reservoir. The wind speed increased consistently during each month of the year, at times being in excess of 3 m s−1. A physical explanation for this and other findings of the investigation are proposed, and it is seen that the observational findings are supported by theory. From this, it is concluded that the construction of a reservoir can indeed change the Weather and/or climate of its surroundings.
