270 



[chap. 4 



potential temperatures of air in thermal equilibrium with the sea ; the water 

 temperatures were obtained from the records of the R.V. Atlantis which was 

 working from the United States east coast to Bermuda on the day of the air- 

 craft flight and previous days. 



Homogeneity is the outstanding feature of the air-mass occupying the area 

 around Bermuda and extending 300 km along the course of the aircraft. 

 Throughout all of this region and up to 1000 m elevation, the potential tem- 

 peratures were all within a degree of one another. The air-mass, continental in 



16 

 I 4 00 H 



22 JANUARY, 1955 



BERMUDA 

 



r- 



RHODE ISLAND 



100 200 300 400 500 600 700 800 900 1000 I 100 

 Distance (km) 



Fig. 84. Heat flux cross-section for same Bermuda-Rhode Island flight. (After Bunker, 

 1957, Fig. 1. By courtesy of the American Meteorological Society.) 



Values of heat flux, water temperatures and even-valued potential temperature 

 isopleths have been replotted from Fig. 83 to show heat-flvix pattern, computed from 

 aircraft measurements by means of boxed formula. 



origin, was warming slowly ; it was, when observed, only one degree cooler than 

 the water. The heat-flow measurements indicate a transport of about 1 meal 

 cm~2 sec"~i (100 cal cm"2 per day) near the surface throughout the region. This 

 is to be contrasted with flows found to be 5-10 times greater in air-masses fresh 

 from the cold continent, as in the Japan Sea cases described. The turbulence 

 was likewise quite moderate, receiving most of its energy from the decreasing 

 convective activity. These observations coupled with strato-cumulus overcast 

 give a good description of the final stages of air-mass modification over the 

 ocean. 



The negative shearing stresses arise from the direction of flight and the 

 shifting of the winds from 300° near the surface to 250° at 850 mb. Thus the 



