Clouds and Radiatively Induced Circulations

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 understood, 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 profile 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. This chapter explores advances in research of the coupling between clouds and radiatively induced circulations and identify the paths forward. The chapter is organized into three sections. Section 1 discusses the relationship between clouds and tropospheric diabatic circulations in which condensate and precipitation are produced. Section 2 focuses on low clouds and shallow radiatively induced circulations in the boundary layer and lower free troposphere. Section 3 focuses on tropical high clouds and the circulations induced by the CRE-AH in these clouds. All the radiatively induced circulations discussed in the three sections are illustrated in Fig. 1.

Radiative Heating of High‐Level Clouds and Its Impacts on Climate

“…High-level clouds form predominantly in the tropics as a result of deep convection, in the storm track regions because of synoptic ascent and due to orographic forcing (Gryspeerdt et al, 2018;Krämer et al, 2020;Wernli et al, 2016). Therefore, their radiative interactions lead to distinct patterns of diabatic heating and cooling within the atmosphere that can influence atmospheric circulations (Dinh et al, 2023).…”