Clouds and radiatively induced circulations (Invited Chapter for the AGU
Geophysical Monograph Series “Cloud Physics and Dynamics: Showers and
Shade from Earth’s Atmosphere”)
Abstract
In the atmosphere, there is an intimate relationship between clouds,
atmospheric radiative cooling/heating, and radiatively induced
circulations at various temporal and spatial scales. This coupling
remains not well under- stood, which contributes to limiting our ability
to model and predict clouds and climate accurately. Cloud liquid and ice
particles interact with both shortwave (SW) and longwave (LW) radiation,
leading to cloud radiative effect (CRE). The CRE includes perturbations
of the radiative fluxes at the top of the atmosphere (TOA) and the
surface, as well as perturbations of the radiative cooling pro- file
within the atmosphere. The effect of clouds that results in atmospheric
radiative heating or cooling that is distinct from the clear-sky
radiative cooling profile will be termed the CRE on atmospheric heating,
or CRE-AH. The CRE-AH can significantly modify the horizontal and
vertical gradients of the diabatic heating profile, inducing
circulations at various scales in the atmosphere. In turn, circulations
govern cloud formation and evolution processes and therefore the
properties and distribution of clouds.