Cloud Distributions over the Tropical Oceans in Relation to 
Seale Flow Patterns ':2 
Joanne 8. Matkus anp CiLAupE RONNE 
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 
Introductory Remarks by Dr. Joanne Malkus—We will come down one step in 
the hierarchy of scale motions and discuss the relations between individual clouds 
and precipitation and traveling cloud systems. We enter now into the synoptic 
scale of motions over the tropical oceans. As Dr. Namias pointed out, these scales 
are associated with and certainly influenced by the large planetary scale. This 
next paper is a condensation of the results on the relationship of the clouds over 
the tropical Pacific Ocean to large-scale flow patterns. 
Abstract—The relations between tropical cloud patterns and the three-dimensional 
synoptic structure have been studied by quantitative time-lapse photography from the 
regularly scheduled MATS aircraft in the North Pacific. From the films of three cir- 
cuits of this oceanic area a “Tropical Whole Sky Code’ was devised. Its application 
proved relatively objective and reproducible; useful deductions concerning the large- 
scale flow from the code numbers and vice versa are possible. The code numbers were 
used as underlays in the synoptic analyses; in addition detailed cloud maps were con- 
structed by simplified photogrammetry in particularly mteresting areas. Preliminary 
results show first that in the tropics, large Cumulus clouds and precipitation are highly 
concentrated in convergent, or disturbed zones, and second that organization of clouds 
into rows parallel to the low-level flow is common, with increasing intensity and wider 
spacing between rows as the degree of disturbance increases. The importance of study- 
ing cloud physics and dynamics in the context of the overall synoptic situation is 
Large- 
brought out. 
Tropical Pacific clouds in relation to the large- 
scale structure of the atmosphere formed the 
subject of this investigation. The method em- 
ployed was quantitative time-lapse photography 
from the scheduled military aircraft flying be- 
tween Hawaii and the Phillipines, from which 
measurements and cloud maps were made by 
triangulation, together with a detailed synoptic 
analysis at all levels between the surface and 
100 mb which was carried out at the University 
of Chicago by H. Riehl and William Gray. 
Our results, as far as cloud physics is con- 
1This paper has been condensed from material 
developed in a joint investigation by the Woods 
Hole Oceanographic Institution and the University 
of Chicago and presented in preliminary form in a 
Technical Report (Woods Hole Rep. No. 58-62) 
by Riehl, Gray, Malkus, and Ronne [1959], which 
was distributed to all participants at the Conference 
and is referred to here simply as “the Report.” 
Approximately one-third of the presentation at 
the Conference consisted in showing a selected 
portion of the aerial cloud motion picture films, 
which were the basic data of the study. 
* Contribution No. 1051 of the Woods 
Oceanographic Institution. 
Hole 
45 
cerned, may be summarized in one sentence: In 
the tropics the precipitation process must be 
studied in the context of the synoptic patterns, 
which regulate the size, structure, development, 
and organization of the clouds and cloud groups 
observed. We plan to illustrate this pomt and 
our method of utilizing our photographie data 
quantitatively, by showing one small portion of 
the film, the corresponding synoptic charts and 
deductions drawn from these jointly, but. first 
we must lead up to the questions we formulated 
by presenting some background material. 
The classical picture of convection in the 
tropics might suggest a statistically both random 
and, on the average, invariant distribution of 
clouds over low-latitude oceans. In the vertical, 
the tropical atmosphere is usually conditionally 
unstable from cloud base upwards, frequently 
to the tropopause; buoyant energy would thus 
nearly always be available for a hypothetical 
non-interacting convective parcel. Horizontally, 
sharp air-mass contrasts are virtually non-ex- 
istent; the low-level atmosphere is well-loaded 
with moisture and closely coupled by vertical 
