## 3 Results
### Sample Dates
#### 3.1.2 Cluster Analysis
In line with the aforementioned results Figure 10c (10d) shows that the T\({}_{\rm b}\) (CTH) distribution was shifted towards greater (lower) values of the corresponding scales. Figure 8d-f shows that pixels in cluster 2 spanned the entire domain. Nevertheless, the abundances for the colder pixels seemed to be greater for latitudes beyond 30 \({}^{\circ}\)S. Cloud decks that surround cluster 1's higher clouds in the region of the UTJ-associated Cis (cf. Figure 7a,b) were well represented by this cluster; most of the pixels along the SACZ and portions of the occlusion in the Atlantic (cf. Figure 7c,d) also were. Cluster 3's number of pixels in Figure 8g-i dramatically increased with respect to the former two clusters to account for 58%, 43% and 52%, respectively, of the total number of pixels in the original T\({}_{\rm b}\) images (not shown). Pixels in these images spanned the entire domain. The mean T\({}_{\rm b}\) values for Figure 8g-i were 278 K, 280 K and 279 K, while the SD was 13 K, 10 K and 11 K, respectively (Table 2). In terms of CTH, the mean values were 2.16 km, 2.94 km and 2.98 km and the SD equaled 1.15 km, 1.39 km and 1.28 km, respectively. The T\({}_{\rm b}\) and the CTH distributions (Figure 10e,f) were in agreement with these results. Moreover, these two histograms were sharper than the previous ones. As with  
Figure 9: Silhouette diagrams for the clusters shown in Figure 8: (**a**) 1 August 2011, (**b**) 4 January 2014 and (**c**) 12 October 2016.  
cluster 2, the colder pixels in Figure 8g-i spanned the domain's lower portion. A feature shared by these three figures was the presence of yellow-red pixels both off the Chilean and the Peruvian coasts and off the Angolan and the Namibian coasts (the African continent was out of sight in all the panels of Figure 8). These pixels were located in regions where persistent stratocumulus (Scs) occurs [73; 74]. Scs are usually found below 2000 m independent of the Earth's region (WMO 2019). Some of the pixels that wrap around the occlusion in the Atlantic (cf. Figure 7d) were included in this cluster (Figure 8h). Figure 8j-l shows the configuration of cluster 4 on the selected dates. The number of pixels represented in them accounted for 20%, 42% and 29%, respectively, of the total number of pixels in the input images (not shown). Aside from Figure 8k, these percentages marked a difference in that they included fewer pixels than cluster 3. As with cluster 2 and 3, all latitudes were spanned by cluster 4's pixels on the selected dates. Reddish pixels were by far the most abundant in all three cases. The T\({}_{\rm b}\) mean value for Figure 8j-l was 278 K, 285 K and 284 K, respectively, while the SD values were 12 K, 9 K and 11 K, respectively. As to CTH, the mean values were 1.22 km, 1.61 km and 1.44 km, respectively; the SD values equaled 0.92 km, 1 km and 0.84 km, respectively (Table 2). The histograms of T\({}_{\rm b}\) for clusters 3 and 4 bore a resemblance both in the shape and in the support. By contrast, the CTH  
Figure 10: Frequency distributions on the selected dates for (**a,b**) cluster 1; (**c,d**) cluster 2; (**e,f**) cluster 3 and (**g,h**) cluster 4.  
cluster 4's distributions shifted towards the lowest values, with the class intervals that had a noticeable contribution extending through 5 km (Figure 10h).