ABSTRACT
Convecting cloud-topped boundary layers a few hundred meters to 2 km deep typically overlay more than half of Earth's surface. They playa vital role in Earth's radiation balance and the exchange of moisture, heat and momentum between the atmosphere and ocean and land surfaces. Boundary layers capped by layer clouds, or stratocumulus, are common over cold surfaces, while shallow cumuli are seen over warmer surfaces. The boundary layer and its cloud are maintained by an intimate set of feedbacks between the cloud layer, radiative cooling, surface fluxes, precipitation, turbulence, and entrainment of air from above the boundary layer. Using the subtropical marine boundary layer as an example, we use observations and models to discuss these feedbacks and how changing surface and above-boundary layer conditions bring about changes in boundary layer and cloud structure.
