Cloudy skies

The atmosphere is remarkably cloudy. On average, clouds cover more than 50% of the atmosphere. Some latitudes even have a mean cloud cover exceeding 80%.

How do clouds, in particular convective clouds,
impact our weather and climate?

With a group of motivated scientists I try to unravel the role of convective clouds, with a special focus on how they influence the winds that carry them around. Read more about my research and that of my group below, including the CloudBrake project funded by the European Research Commission.


Do clouds slow down circulations critical for climate?

The ERC Starting Grant project CloudBrake project (2017-2022) strives to expose relationships between shallow clouds and the vertical structure of wind, and to estimate the amount of cumulus friction that takes place in different large-scale flows, such as in the large-scale Hadley circulation. A better understanding of cloud-wind interactions is important for numerical weather prediction, climate modeling, and wind energy design. The research carried out combines high-resolution modeling (Large Eddy Simulation) and global modeling with the analysis of existing and new observations from ground and from space.

Tracing convective momentum transport in complex cloudy atmospheres

Clouds often visualize how the wind blows, but rarely are cloud measurements used to understand how clouds themselves change winds. The NWO VIDI project CMTRACE (2019-2024) will combine unique measurements with fine-scale simulations to unravel the patterns of wind in diverse cloud fields. Scanning wind lidars and cloud radars deployed at the Ruisdael Observatory (Netherlands) and the EUREC4A Field Campaign (North Atlantic trades) will take unique measurements of winds through clouds. By coupling these novel measurements to Large Eddy Simulation output, CMTRACE will identify mechanisms that are key to convective momentum transport (CMT). New data and acquired insights will be used to improve weather prediction models.

Research themes

Trimodal convection

In nature, moist convection prefers three modes: shallow, congestus and deep cumulus. Using a conceptual model, can we understand what processes help set the depth of convection in tropical circulations?

Warm rain over oceans

Warm rain is that produced by clouds with tops below the freezing level. Observations reveal that warm rain is a significant part of rainfall over global oceans, with implications for atmospheric dynamics.

Vertical structure of low cloud

Global models disagree on how low clouds respond to increasing carbon dioxide concentrations, and observations show how this behavior might relate to the vertical structure of low cloud produced by models.