Fig. 9: Schematic diagram illustrating how cloud radiative effects (CREs) enhance upstream diabatic heating and promote block formation. | Nature Communications

Fig. 9: Schematic diagram illustrating how cloud radiative effects (CREs) enhance upstream diabatic heating and promote block formation.

From: Cloud radiative effects significantly increase wintertime atmospheric blocking in the Euro-Atlantic sector

Fig. 9: Schematic diagram illustrating how cloud radiative effects (CREs) enhance upstream diabatic heating and promote block formation.

In the warm conveyor belt (WCB) upstream of the block, enhanced diabatic heating arises from latent heating (LH), driven by moisture transport inflow, and from longwave (LW) cloud radiative effect (LWCRE), as high clouds absorb outgoing LW (infrared) radiation. LWCRE further amplifies LH through a positive feedback by intensifying large-scale ascent and moisture transport within the WCB. This CRE-LH coupling strengthens the upstream diabatic source of wave activity (ΔΣ), which increases downstream convergence of horizontal local wave activity flux and hence, favors blocking formation. In the absence of LWCRE, this feedback is weakened, leading to reduced ascent, moisture transport, and LH, and thereby suppressing the diabatic wave source and its downstream impact.

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