. The future water supply of San Francisco; a report to the Honorable the secretary of the interior and the Advisory board of engineers of the United States army . ervice on evaporation and wind experiments were made with the air at atemperature of 84° and a relative humidity of50^r, by whirling Piches Hygrometers at vary-ing velocities on an arm 28 feet in length. Theevaporation was found to be times as greatwith a velocity of 5 miles as in a calm, timesat 10 miles, times at 15 miles, times at 20miles, times at 25 miles and times at 30miles an hour. Thes
. The future water supply of San Francisco; a report to the Honorable the secretary of the interior and the Advisory board of engineers of the United States army . ervice on evaporation and wind experiments were made with the air at atemperature of 84° and a relative humidity of50^r, by whirling Piches Hygrometers at vary-ing velocities on an arm 28 feet in length. Theevaporation was found to be times as greatwith a velocity of 5 miles as in a calm, timesat 10 miles, times at 15 miles, times at 20miles, times at 25 miles and times at 30miles an hour. These results, plotted on PlateD2, show that the evaporation due to the in-crease of wind velocity is very rapid at first butgradually decreases until at after 30 or 35 milesan hour the evaporation is but little affected byincreased wind velocity. Of experiments made at the Colorado StateAgricultural College, on evaporation, the Agri-cultural Experiment Stations Bulletin No. 45says (page 18): The effect of the wind Is to increase theamount of evaporation by bringing unsatur-ated air in contact with the water, and togive opportunity for the diffusion of the 385. J?;o H! o ft H a K ei M H 03 oj o I—I p2 Eh OW w o 02 H> O 386 EVAPORATION INCREASES WITH TEMPERATURE. 387 water vapor. Prom the working formuladerived from the observations in 1889, eachmile of wind increased the evaporation byabout 2 per cent. Mr. Fitzgeralds experi-ments at Boston indicate an increase of 2 percent for each mile of wind. Evaporation is further shown to be closelygoverned by wind velocity by Plate D3, takenfrom U. S. Department of Agricultures Bulle-tin No. 248.
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Keywords: ., bookcentury1900, bookdecade, booksubjectwatersupply, bookyear1912
