1068 
condensation. When the quantity is negative, it indi- 
cates that an excess of latent energy is being locally 
transformed into sensible heat. However, since the 
author has already computed the seasonal and annual 
differences between evaporation and precipitation over 
the oceans [10], the difference (Q, — Q px) can be de- 
MARINE METEOROLOGY 
ing that the Northern Hemisphere oceans are not 
sources of water vapor as surplus latent energy during 
this season. 
Albrecht [1] has prepared a rough annual chart, 
showing (# — P) over the oceans, which is based upon 
a comparison between observed surface salinities and 
Fie. 5.—The annual values of the surplus of energy available in the latent form of water vapor [Qa — Qn, = L: (E — P)], 
expressed in calories per square centimeter per day. (The values above can be converted into rough # — P rates by considering 
that the isometric interval of 50 cal em™ day™ is approximately equivalent to an excess rate of evaporation over precipitation 
of 12 in. yr!. Negative values indicate a corresponding excess of precipitation over evaporation.) 
TaBLe VIII. Seasonat VaLuns or Qa — Qp, IN DirreRENT LatirupEe Zones (in cal em day—!) WHERE 
Qa — Qn = Li (E- P) 
North Atlantic North Pacific 
North latitude zone 
Dec.—Feb. Mar.-May June-Aug. Sept.—Nov. Dec.—Feb. Mar.—May June-Aug. Sept.—Nov. 
0°-10° — 62 —57 —126 —64 —34 —70 =e) —78 
10°-20° 162 155 95 84 145 141 48 25 
20°-30° 133 103 85 114 155 111 78 143 
30°—40° 162 68 36 142 114 19 —10 125 
40°-50° 57 —17 —72 24 —3 —66 —96 —28 
50°-60° 78 —21 —74 —19 —13 —118 —89 —79 
termined very simply through use of these data and by 
applying the expression 
Qa — Qo, = 6.48 (H, — P,) calem~ day~!, (22) 
when n = 91 and L; = 585, and #, and P, are the sea- 
sonal values of H and P expressed in grams per square 
centimeter per season. 
The annual values of (Q. — Qpn) are given in Fig. 5 
and the seasonal averages for latitude zones are given 
in Table VIII. These data show that the surplus latent 
energy is derived almost entirely from the ocean areas 
between 10°N and 40°N. The values are greatest in 
nearly every latitude zone during winter; during sum- 
mer the quantity (Q, — Q>,), averaged for the entire 
North Atlantic and North Pacific, is negative, indicat- 
those computed by means of Wiist’s formulas [89] 
which give surface salinities as a function of (H — P). A 
comparison between Albrecht’s chart and Fig. 5 shows 
that the two agree in the gross features. However, the 
centers of Albrecht’s areas of maximum (H — P) are 
displaced from the positions indicated on Fig. 5. This 
displacement would be expected on the basis of the 
horizontal oceanic circulation which tends to shift the 
areas of maximum salinity in the direction of surface 
flow away from the centers of maximum (H — P). 
Wiist’s formulas apply regionally only in the absence 
of significant horizontal transport. Therefore, any 
(EZ — P) chart based upon an examination of the dis- 
tribution of surface salinities will show important re- 
gional departures from the true distribution [9]. 
