206 



[chap. 4 



between +2°C and — 1°C. Fig. 51a is typical of the wind, temperature and 

 moisture traces when the sea temperature exceeds that of the air by the normal 

 amount. Such records, now available in large quantities, demonstrate that 

 fluctuations on the horizontal scale of 50-300 m are the rule, with amplitudes 

 of several knots in wind speed, 0.5-1.0°C in temperature, and 1 mb in vapor 

 pressure (~0.6 g/kg in specific humidity). These records suggest, and longer 

 records confirm, that larger "eddies" also occur. These may have dimensions 

 from 10-50 km. 



The measurements shown in Fig. 51a were made near Puerto Rico (at 



(a) 



2 3 4 5 6 7 8 9 10 II 12 13 

 Air Distance (thousands of yards) 



-* 69 



Fig. 51. Fluctuations of atmospheric parameters measured from deck of Woods Hole 

 research vessel under varying conditions as function of air distance (wind speed times 

 time). (After Wyman et al., 1946, vmpublished.) 



(a) Typical profile obtained when ship stationed in western tropical Atlantic, north 

 of Puerto Rico (19° 30'N, 66°W). Fluctuations of wind (knots), temperature (°F) and 

 vapor pressure (mb). Sea minus air temperature ~0.6°C. Surface wind from 040° at 

 14 mph ; cumulus base 1700 ft, April 23, 1946. 



(b) Typical profile obtained when ship stationed in eastern tropical Pacific, south of 

 Panama Canal Zone during March, 1946. Profiles of wet-bulb temperature (°F above) 

 and dry-bulb temperature (°F below). Sea minus air temperature minus 3.5°C. Wind 

 speed 15 knots. 



