The average annual evaporation of the oceans in different latitudes can be considered fairly well established (Mosby, 1936, Wtist, 1936), but so far little is known as to the character of the annual and the diurnal variations. Helland-Hansen (1930) has pointed out that evaporation will be facilitated if the sea surface is warmer than the air, whereas evaporation will decrease or cease if the sea surface is colder....