Fig. 1
From: Impacts of orography on large-scale atmospheric circulation
Orographic effects on atmospheric circulation. a Island wake effects revealed by cloud-free regions in the lee of the Canary Islands, and von Karman vortices highlighted by the cloud spirals further downstream (Photo from the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE, on 24 April 2000 used with permission from Visible Earth NASA); b Classical ‘v’ shape distinctive banded lee-wave pattern is visible in the clouds downstream of the Crozet Island over the southern Indian Ocean. The lifting and cooling of air on the crests of these waves lead to cloud formation, while sinking and heating leave the troughs cloud-free. (Photo from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on 9 April 2014 used with permission from Visible Earth NASA); c Downslope windstorms can lead to severe accelerations of the near-surface winds on the leeward side of the mountain, when the vertical propagation of waves is prevented by an elevated inversion-like region created by the breaking of large-amplitude waves close to the mountain top. Adapted from Whiteman.76 d Longitudinal variation of the disturbance of the geopotential height in the Charney–Eliassen model compared to the observed 500-hPa geopotential height perturbations at 45 N in January (top) and smoothed profile of topography at 45 N used in the Charney–Eliassen model (bottom). (Redrawn after Holton.77 with permission from Elsevier)
