Tropical cyclones require warm ocean waters, typically above 26.5°C, to form and intensify. They also need the Coriolis force to initiate rotation. While the Coriolis force is present, albeit weaker at lower latitudes, the primary reason for the absence of cyclones in these specific South Atlantic and South-Eastern Pacific regions is the infrequent presence of the Inter-Tropical Convergence Zone (ITCZ) in those locations, which is a crucial area for convective activity and cyclone genesis.