AOPP Seminar - Stratocumulus-cumulus transitions sensitivity dependence on environmental factors

Stratocumulus clouds are white "veils" of clouds that cover hundreds of kilometers large regions over subtropical oceans, typically to the west of continental landmasses. These clouds are an important ``coolant'' of the climate system because they reflect a substantial amount of sunlight back to space. As the environmental conditions change (e.g., sea surface temperature increases) these clouds naturally break up into isolated cumulus clouds. These cumulus clouds have drastically less cooling power because they cover much less area. In terms of climate change it is important to understand whether transitions to cumulus would happen sooner rather than later, hence amplifying global warming. However, even our most accurate models of climate have trouble agreeing on how to simulate stratocumulus clouds. Here we develop a theoretical model to help us better understand what conditions affect the transition the most. We show that changes in global circulation, rather than direct CO2-induced warming effects, are most important for when (or whether) a transition will happen. We then briefly discuss the implications of this finding, what new research it motivates, and how our conceptual model can be used to further deepen our physical understanding of the stratocumulus-cumulus transition.