HUMIDITY 
Table 44. Mean hourly values of vapor pressure in millimeters for groups, 
Carnegie, 1928-29--Concluded 
Local mean hours 
pee fs | ae [ [1s Tas] wpm fe fp a 
mm mm mm mm mm mm mm mm mm mm mm 
I 8.26 8.16 8.30 8.21 8.16 8.08 8.06 8.06 8.01 8.06 7.98 
I 12.93 12.85 12.71 12.80 12.78 12.67 12.41 14.42 12.59 12.55 12.63 
I 21.34 21.59 21.50 21.64 21.42 21.04 21.04 20.96 20.84 20.90 21.00 
Iv 21.99 21.85 21.75 21.46 21.30 21.16 21.11 21.11 21.13 21.28 21.43 
Vi s23.05 22.99 22.85 22.66 22.74 22.47 22.23 22.35 22.35 22.49 22.7 
VI 21.13 21.01 21.07 21.02 20.92 20.91 20.89 20.89 20.86 20.89 20.92 
vil 
&) 15.23 15.23 15.10 15.11 15.09 15.05 14.91 15.00 15.05 14.94 15.08 
(b 18.81 18.72 18.65 18.59 18.53 18.48 18.49 18.59 18.43 18.41 18.59 
VII 12.93 12.91 12.88 12.76 12.83 12.72 12.68 12.71 12.66 12.69 12.84 
ix 13.93 14.00 13.93 13.85 13.64 13.51 13.52 13.48 13.31 13.31 13.43 
x 17.40 17.28 17.28 17.38 17.12 17.10 17.17 17.10 17.08 17.10 17.20 
XI «621.39 «21.30 =. 20.86 20.94 20.96 20.84 20.96 20.98 21.07 21.01 21.09 
XI 821.83 =. 21.65 21.70 21.84 21.66 21.71 21.88 21.88 21.77 21.95 21.68 
xi 
si 15.88 15.95 15.99 15.93 15.84 15.7 15.74 15.71 15.82 15.92 15.90 
) 10.80 10.83 10.77 10.87 10.71 10.61 10.71 10.81 10.75 10.81 10.79 
XIV 8.70 8.57 8.60 8.57 8.56 8.58 8.64 8.67 8.68 8.73 8.65 
XV =10.70 10.70 10.88 10.76 10.64 10.79 10.64 10.75 10.72 10.66 10.54 
XVI 12.17 11.99 12.34 12.30 12.44 12.24 12.19 12.21 12.19 12.10 12.18 
XVII 
(a) 14.76 14.69 14.68 14.45 14.30 14.43 14.51 14.53 14.64 14.49 14.59 
(b) 17.66 17.65 17.71 17.65 17.40 17.48 17.31 17.33 17.36 17.36 17.52 
(c) 16.75 16.79 16.78 16.68 16.43 16.43 16.62 16.63 16.66 16.7 16.73 
XVID =. 20.77 20.63 20.61 20.65 20.65 20.62 20.67 20.69 20.92 20.87 20.82 

Days omitted as follows: (a) Aug. 25, 26; (b) Dec. 3-12; (c) Dec. 25, 26; (d) Mar. 4, 13-20, 26; 
(e) May 6, 11, 20-25; (f) June 8-24; (g) Two dates July 14 on crossing 180° meridian; (h) Sep. 20-Oct. 2 
(i) Oct. 18. 
DISCUSSION OF VAPOR PRESSURE 
Mean Vapor Pressures for Groups 
The mean hourly values of vapor pressure for the 
various Groups are presented in table 44. It may beob- 
served that the variation from group to group of the 
Table 45. Absolute maximum and minimum vapor 
pressures for groups, Carnegie, 1928-29 
| Daily range 
Group | Maximum | Minimum ininaan 
mean hourly vapor pressures is very similar to the 79.2 a rES 20 at 
corresponding variation of the mean hourly sea and air : 7 ‘ ? : 
II 20.2 8.9 6.2 1.3 
temperatures. Obviously, vapor pressure is largely a Im 94.2 17.3 3.9 23 
function of air and sea temperature. IV 24.9 7827 4.0 1.5 
Vv 25.55 19.7» 4.2) 1.0 
Maxima and Minima of Vapor Pressure oe ie — rag a 
The absolute maximum and minimum vapor pres- @} 20.1 11.4 5.0 0.5 
sures for the various groups are presented in table 45. Vu ak as a 
As would be expected, the higher vapor pressures were IX 16.7 10.1 33 Li 
recorded in the tropics. The absolute maximum vapor xX 19.6 14.7 3.0 i2 
pressure (25.5 mm) was recorded at 06h, October 10, XI 24.3 18.0 3.7 0.9 
1928, in latitude 10°3 north, longitude 79°3 west. The XII 24.2 18.0 3.4 0.6 
air temperature at this time was 27/4, the sea-surface xi _ b 
temperature 28°5. The absolute minimum vapor pres- (a) 21.5 10.9 4.7 1.8 
sure (6.8 mm) was observed at 18h, July 8, 1929, in lat- (b) 12.6 ae 7 a = a 
itude 46°9 north, longitude 163° west. The air tempera- eo is ne 28 0.6 
ture on this occasion was 6-8, the sea-surface tempera- XVI 13.8 10.4 2.3 0.8 
ture 6°9. It may be remarked that the minimum sea- XVI 
surface (6°4) and the minimum air (6:3) temperatures (a 17.3 12.1 2.9 0.9 
were also registered on this date, the former at noon (b 21.7 15.4 4.1 1.0 
and the latter between 19h and 20h. (c 22.0 11.8 3.9 0-9 
XVII 23.1 17.6 3.6 0.7 
The greatest daily range in vapor pressure (5. 2mm) 
occurred on November 2, 1928, between the Gulf of Pan- 
_ ama and the Galapagos Islands. The sky was overcast 
during this period, with frequent rain squalls. The least 

2 Absolute minimum values for cruise. 
Absolute maximum values for cruise. 
