Cumulus clouds ('fair-weather clouds') form as a result of atmospheric convection and have vertical extents between a few hundred metres (humilis species) and several kilometres (congestus species). They are a major source of uncertainty in the estimation of climate sensitivity by climate models. In order to reach more agreement in cloud changes due to global warming as predicted by different climate models, a better understanding of the physics of these clouds is needed. Shallow cumulus clouds are particularly common over the oceans of Earth's trade-wind regions, which are situated roughly between the 10° and 30° parallels on both hemispheres and are characterised by steady easterly surface winds. These winds are part of the Hadley cell, a large-scale circulation system in which air flows away from the equator at high altitudes and towards the equator near the surface. As a consequence, vertical shear (i.e. vertical differences in wind speed and direction) is common in this region. While recent studies have shown that (surface) wind speed is an important predictor of cloudiness in this region, little work has been done to elucidate how shear affects clouds. Vice versa, clouds also affect the wind by vertically transporting it. While this convective momentum transport (CMT) undoubtedly plays an important role in the force balance that sets the trade winds, only little is known about the details of how CMT sets the vertical structure of the wind and of the spatial scales of th