230 



Journal of Agricultural Research 



Vol. X. No. 5 



EFFECT OF TEMPERATURE UPON EVAPORATION 



As has been noted previously, the temperature 'efifect upon evapora- 

 tion was observed, primarily, for calibration by means of similar tanks 

 heated to diflferent temperatures. Thus, the variable is temperature, 

 all other factors remaining the same. Figure 5 shows graphically the 

 results indicated in Table VIII. 



Table VIII. — Relation of evaporation from small wai^r surface to temperature of water 

 surface, all other conditions being similar 



In this connection attention is called to Table IX, showing tempera- 

 tures at different points from the top to the bottom of the deeper tanks 

 in use at the laboratory. The first set of temperatures recorded were 

 early in the season, before the lower water had become warm, but on 

 a warm day. The second measurement, on a cold day in May, shows 

 how the whole water body has warmed up, and, though the air tem- 

 perature is low, the heat storage effect of the water keeps its temperature 

 above that of the air. Similar variations throughout the season are of 

 interest. The temperature variations in the different-sized tanks are 

 also brought out. 



