
4 METEOROLOGICAL RESULTS OF LAST CRUISE OF CARNEGIE 
Maxima and Minima of Pressure 
The absolute maximum pressure during the cruise 
(773.7 mm) was recorded at 21h, December 26, 1928, at 
latitude 40° south in longitude 97° west, near the center 
of the South Pacific High-Pressure Belt. The absolute 
minimum pressure (744.9 mm) occurred between 11h 
and 12h on June 6, 1929, at latitude 35° north in longitude 
141° east, while the Carnegie was hove to on the south- 
ern edge of a typhoon. 
The highest daily mean pressure also occurred on 
December 26, 1928, the same day on which the absolute 
maximum pressure was recorded. The lowest daily 
mean pressure occurred on June 7, 1928, at latitude 50° 
north in longitude 8° west. Between 21h and 22h on this 
date the pressure (746.2 mm) averaged only 1.3 mm 
higher than the absolute minimum pressure recorded on 
June 6, 1929. On this date, however, the rate of fall was 
only 4 mm in twenty-four hours, whereas at the time of 
the typhoon, the barometer fell 12 mm during 11h on 
June 5 to 11h on June 6, 1929. Another very rapid pres- 
sure fall was recorded on May 22 and 23, 1928, while 
the Carnegie was crossing the North Atlantic. During 
this period the barometer fell from 764.9 mm at 23h on 
May 22, to 753.0 mm at 23h on May 23, afallof 11.9mm. 
On this occasion the wind blew from the northezst with 
Table 3. Mean atmospheric 
pressure for latitude ranges, 
Carnegie, 1928-29 
Latitude No. Mean 
range days pressure 
° ° mm 
55-65 N 17 758.50 
45-55 N 38 760.01 
35-45 N 32 762.99 
25-35 N 38 761.44 
15-25 N 32 760.85 
5-15 N 43 759.10 
5N-5S 29 758.66 
5-15 S 45 758.47 
15-25 8S 33 760.44 
25-35 S 22 765.54 
35-45 S 9 771.08 
otalidays) 338) 9 eerccace 
Mean all latitudes 761.55 
Mean all days 760.72 
gale force, indicating that the Carnegie at the time was 
on the northern periphery of an unusually well-developed 
extratropical cyclone (see appendix III, table 77). 
Data concerning the greatest mean maximum pres- 
sures for the several ranges of latitude are presented in 
table 4. This table shows that the greatest mean pres- 
sures occurred in the two subtropical high-pressure re- 
gions; the greatest daily maximum pressure occurred in 
the range of latitude 35° to 45° south (771.9 mm), and 
the next highest mean pressure occurred between lati- 
tudes 35° and 45° north. The lowest mean daily mini- 
mum pressure occurred in the range of latitude 55° to 
65° north. 
Daily Amplitudes of Atmospheric Pressure 
The data on atmospheric pressure have been collect- 
ed and summarized for each ten-degree range of latitude 
beginning with latitudes 65° north and 45° south. 
These values may be taken as representative of the con- 
ditions for the approximate latitudes 0°, 10°, 20°, 30°, 
40°, 50°, and 60° north and 10°, 20°, 30°, and 40° south 
(the mid-points of the latitude ranges). The mean hour- 
ly values of pressure within each of the ranges of lati- 
tude have been corrected for noncyclic change deter- 
mined from the difference between the mean values of 
pressure at 00h and at 24h. The correction has been ap- 
plied linearly to the mean values for each of the twenty- 
four hours, one-half of the difference being applied at 
OOhand at 24h. Theresults of these computations are pre- 
sented tabularly in table 5 and graphically in figure 4. 
The last two lines of table 5 give respectively the 
average departure and the amplitude (difference between 
highest and lowest mean departure). 
The unperiodic daily amplitude measured by the dif- 
ference between the mean daily extremes is seen to be 
greatest between latitudes 45° and 65° north (table 6). 
It is to be noted that this is in direct contrast with the 
periodic daily amplitude measured by the difference be- 
tween the highest and lowest hourly means, which is 
smallest in these latitudes. This can be explained by a 
consideration of the frequency of certain ranges of am- 
plitude according to latitude (table 6). The greater fre- 
quency of days with amplitudes less than 4 mm south of 
latitude 30° north, and the greater scattering of the 
ranges north of this latitude, account for this increase 
in unperiodic amplitude with increasing latitude. 
Table. 4. Mean and extreme values of atmospheric pressure for latitude ranges, Carnegie, 1928-29 

65°N- | 55°N- | 45°N- | 35°N- | 25°N- | 15°N- pie 
55°N | 45°N | 35°N | 25°N| 15°N 5°N 

Latitude range 

5°S- 
15°S 


Mean mm mm mm mm mm 
Daily 158.! 5 760. 1 762.4 761.5 760.8 759.1 Cay yee OE a Ayala 
Maximum 160°2  761-°9" 76325) 76228" “76128 76022) 160!0) 9 17596) seGl.b)) OG. 4emmniLeo 
Minimum 19652 %58.4> 761-5 T6022 475958 oeoe Doub OLS Ota O re 
Amplitude 3.5 3.5 2.0 PAs .0 2.3 2.7 2.4 Poa iy end, 
Absolute 4, 
Maximum 767.4 770.1 769.9 769.6 764.8 762.4 763.0 763.7 766.6 769.2 773.7% 
Minimum 747.7 746.2 751.3 744.96 757.7 753.7 753.8 753.9 755.6 759.8 766.2 
Amplitude 19.7 23.9 18.6 24.7 ail 8.7 9.2 9.8 11.0 9.4 ea) 

4 Absolute maximum of cruise, Dec. 26, 1928, at ain in latitude 40° south, longitude 97° west. 
Absolute minimum of cruise, June 6, 1929, at 115 and 12h in latitude 35° north, longitude 140° 
east, on southern edge of a typhoon. 
