ere 
ocean per unit area, and let N be the nocturnal radiation. Then the 
het rate at which unit area of the ocean gains heat at the surface is 
S - N = He = Hoe 
Of the individual terms, S is always vositive, N and H, are usually 
positive, H, can often be negative, Of course the sum is sometines 
positive and sometimes negative. 
Omitting from consideration a thin surface film, the density of 
the surface water is being increased if 
tae 
) 
ma Nefative, and it is being decreased if this sum is. positive. 
Sis sida He 1 + 
The unit of area used in the calculations is the souare centi- 
Meters The unit of heat is the calorie, which is the heat used in 
warming one gram of water by one degree centigrades 102 cal em7* 
will warm one fathom of water by one degree Fahrenheit. The unit of 
time is the day. This was chosen because it is much sinpler to work 
with daily totals of solar radiation than with instantaneous values. 
It is usually a simple matter to obtain results for periods shorter 
than a day. If each cuantity is expressed in terms the day as tine 
UHit, the total loss of heat during a l@-hour nisht is for instance 
ive Or Het Bal, 
and the gain of heat during a 12-hour day is 
S = ae) (N Hee Hee 
Department of Meteorolog 
New York University 
October 30, 1941 
