85 



Clearly the fact the atmosphere is fully turbulent complicates the 

 development of quantitative criteria for cloud patterning and makes difficult 

 the assessment of the role of sea-air interaction in modifying or regulating 

 these patterns . However, we can leam much more about these relations if 

 we would only focus our existing observational resources simultaneously upon 

 the sea-air boundary conditions, the air structure, and the cloud patterns. 

 We do not yet know the relative roles of the first two in producing the 

 fascinating cloud configurations that the satellites are showing us . For 

 ex^ple, in Figure ik as we move (from left to right) following the southeast 

 trades toward the equator, the cloud patterns change from cellular to actino- 

 form (Picture of the Month, 1963) to blob-like. Hubert l/ has postulated 

 that in going from cellular to actinoform, heating from below may be giving 

 way to dominant cooling from above. The change to blob form in the equatorial 

 zone may be due to deepening of the convective layer. No data exist to test 

 these interesting and important suggestions. The potential of satellite 

 pictures as a tool to understand and predict tropical weather, to interpret 

 the role of sea-air interaction therein, cannot progress much farther until 

 ship and aircraft observations are jointly f ocussed on these situations . The 

 large necessary expenditure dwindles when compared to that of the space 

 program . 



A problem to isolate for the next step of the investigation might be 

 the abrupt transitions in oceanic cloud forms . A typical example is shown 

 in Figure 15 . Are these common transitions, often almost infinitely sharp, 

 related to sudden changes in sea temperature or are they governed by swift 

 transitions in air motions? We know they are more abrupt than any likely 

 structural changes in the atmospheric sounding, in terms of lapse rate or 

 humidity stratification. 



The beginnings of the required study were made with the Woods Hole 

 Aircraft (Malkus, 1957' using an airborne radiometer, soundings, and cloud 

 photography. "Warm spots" in the ocean upper layers were found, which were 

 also documented by a research vessel with thermistors at several depths . 

 These warm spots were related to trade cumulus groups observationally 

 (Figure 16) . The "heated island" and "equivalent thermal mountain" frame- 

 work (stem and Malkus, 1953) was used to explain the observations. Even 

 these small-amplitude warm spots should produce an "equivalent thermal 

 mountain" about 100 meters in elevation, which can be quite effective in 

 triggering trade-wind clouds. In continuing these studies, a difficulty is 

 that the airborne radiometer must be flown below 1000 ft., while cloud photo- 

 mapping is much better performed at 10,000 ft. or more. Furthermore, a 

 surface vessel is needed to calibrate the radiometer and to determine the 

 depth of any oceanic temperature anomalies found. Despite these complications, 

 such a program is mandatory to advance the interdependent fields of sea-air 

 interaction, satellite interpretation, and tropical meteorology. 



1/ Personal communication to the writer 



