6 



UPPER -WIND OBSERVATIONS OF LAST CRUISE OF CARNEGIE 



Flight 6 was made about 40 km from one of the Galapa- 

 gos Islands, so that the numerous changes in wind direc- 

 tion observed in this flight may have been because of ef- 

 fects set up by this island group. 



Flights 9 to 16, November 19 to 25, 1928 



These flights were made as the Carnegie sailed 

 southward across an area where southeast trades gen- 

 erally prevail. The Carnegie experienced fair weather 

 with southeast or east-southeast breezes and trade wind; 

 there were cumulus clouds chiefly around the horizon. 

 The surface winds turned from east-southeast to east 

 below 1 km, and in the single flight above 2 km this ro- 

 tation continued to northeast at 3.5 km, which was the 

 greatest height reached. 



Flights 17 to 29, 

 November 26 to December 26, 1928 



The Carnegie ran out of the southeast trade winds 

 about latihide 20° south. From this parallel of latitude 

 southward to 40.°4 south the winds were variable, but 

 mostly from the east. From November 26 to December 

 6, when the Carnegie reached Easter Island, the winds 

 were light; drizzling rain fell on the evening of Novem- 

 ber 29, and rain squalls occurred on November 27 and 

 30, and December 4 and 5. The Carnegie sailed from 

 Easter Island on December 12, 1928, going in a general 

 direction southward and on December 26 reached the 

 extreme southernmost point of the cruise--40.°4 south, 

 97.°4 west. The barometer reading, 773.7 mm, taken 

 here near the South Pacific high-pressure center, was 

 the highest recorded during the cruise. Light to moder- 

 ate breezes prevailed, and the skies were comparatively 

 clear, except for a ring of clouds around the horizon. 

 On December 22 in latitude 36.°9 south, 104.°1 west, fog 

 continued all day and generally hazy conditions were 

 observed for the following week. Rain squalls occurred 

 on December 13, 14, 15, and 19. 



The surface winds from latitudes 20° to 25° south 

 were easterly and from there to 31° south, from north- 

 east. In all cases the winds at increasing heights to 3 

 km above the sea turned counterclockwise to a more 

 northerly direction. The three flights observed up to 6 

 km show a general change back to southeast at this lev- 

 el, whereas flight 21 on December 21 shows southeast 

 winds up to 11 km. In all cases the winds were very 

 light, having a mean velocity based on all three flights 

 from 3 to 6 km of only 3.6 m per second, which is also 

 the mean value of the scant data to 11 km. 



Flights 27, 28, and 29 made on December 18, 20, 

 and 26, although covering a period of eight days and 

 made at points 1700 km apart, showed much similarity 

 of air motion at all levels. The northeast surface winds 

 became northwest at 1 km and remained from this di- 

 rection to a height of 9.5 km, with an extreme observed 

 velocity of 11 m per second. 



Flights 30 to 34, 

 December 30, 1928 to January 8, 1929 



These flights were made as the Carnegie sailed 

 northward across the center of the South Pacific high- 



pressure area during the southern midsummer. Except 

 on January 7, when drizzle and rain occurred in the aft- 

 ernoon, the weather was pleasant, with light breezes or 

 airs generally from southeast and cumulus clouds chief- 

 ly around the horizon. 



At the instants of releasing the pilot balloons, the 

 surface winds were once each calm, southeast, north- 

 west, west, and south -southeast, showing the variable 

 nature of the surface winds. At increasing height above 

 the surface the winds turned through south to a definite 

 southwest drift, which increased in velocity with height. 

 The stratum from 1 to 2.5 km has the most pronounced 

 drift from the south, with velocities of 5 to 6 m par sec- 

 ond. The westerly winds above this height have higher 

 velocities, one of the highest wind velocities observed 

 during the cruise being 19 m per second from west- 

 southwest at a height of 7.5 km in flight 34 (latitude 

 24.°8 south, 82.°1 west). The outstanding feature of these 

 data is the uniformity over a wide extent of southwest 

 winds at levels above 2 km. 



Flights 35 to 39, 

 January 12 to February 6, 1929 



Flights 35 and 36 were made near the South Ameri- 

 can coast en route to Callao in an interval of almost un- 

 interrupted overcast skies. After remaining in Callao 

 harbor from January 14 to February 5, where flight 37 

 was made, the Carnegie sailed for Papeete, Tahiti. 

 Flight 38 was made on the following day, February 6, in 

 pleasant weather with gentle southeast breezes. All 

 flights except no. 35 showed northwest winds above 1 

 km, in opposition to the strong surface southeast trades. 

 In flight 35 southeast winds were found to 4.5 km, prob- 

 ably owing to a low pressure developing off the coast of 

 Chile. 



Flights 40 to 49, February 7 to 16, 1929 



This group of observations was made as the Carne - 

 gie sailed westward from Callao to Tahiti in the first 

 20° of longitude west of South America. Southerly to 

 southeast breezes and airs persisted throughout, with 

 considerable clouds round the horizon, but no rain fell. 

 Flights 40 to 42, made at 14h 12m, 15h 54m, and 17h 

 48m on February 7, showed the same upper winds as 

 found in the flights made nearer the coast. The south- 

 erly surface winds turned to northwest at heights of 2.5 

 km. In both flights 43 and 44, taken on February 9 and 

 11, a thin northwest stratum was found, but flight 43 had 

 above this west -southwest winds to 6 km, and flight 44 

 had west winds. It would thus appear that the west- 

 southwest and westerly winds reach to considerable 

 heights above the southeast trades as one moves out to- 

 ward the Central Pacific from the Peruvian coast. 



Flights 45 to 47, made on the afternoons of Febru- 

 ary 12, 13, and 14, all showed a remarkably solid cur- 

 rent from 4 to 5.5 km moving from northeast, but above 

 8 km the flights on February 12 and 14 showed north- 

 west winds, with velocities on February 12 averaging 16 

 m per second at these levels. Flight 48 showed this 

 abrupt change to northwest at 4.3 km, but the observers 

 reported that at this elevation the balloon was lost 

 through haze or distance, probably caused by a slight 

 amotmt of fog at the surface of discontinuity. 



