Cloud cover, plants, and a changing climate

Spring clouds; May 2020; Iowa, USA
Spring clouds; May 2020; Iowa, USA

Cumulus clouds make a significant contribution to the Earth’s energy balance and hydrological [water] cycle and are a major source of uncertainty in climate projections.”

Sikma, M., & Jordi Vilà‐Guerau, d. A. (2019). Substantial reductions in cloud cover and moisture transport by dynamic plant responses. Geophysical Research Letters, 46(3), 1870-1878. [PDF] [Cited by]

“With an average daily occurrence of around 25% in midlatitude and tropical continental regions, cumulus convection has a significant influence on regional radiation balance and moisture recycling. By perturbing the incoming radiation, cumuli modulate plant stomatal aperture and surface temperature [by shading the plants and land surface] near updraft regions. In this capacity, cumuli initiate a chain of events that dynamically affect their development, as well as the distribution of atmospheric moisture and terrestrial carbon uptake.

Observation‐based experimental and simulation studies have revealed that cumulus radiative perturbations have a bidirectional effect on local photosynthesis and transpiration rates [in plants]. Optically thin clouds enhance those rates, due to an increase in the diffuse radiative component, while optically thick clouds lead to significant decreases in evapotranspiration [the process by which water is transferred from the land to the atmosphere]. In the perspective of moisture recycling, this early transpiration enhancement stimulates cumulus growth and subsequent upward moisture transport, thereby preconditioning the mid‐tropospheric cloud layer for regional‐scale deep convection [thunderstorms] on a subweekly scale. This underlines the predominant role of plant physiology as a key driver related to midtropospheric moisture convection and demonstrates that only a profound understanding of the fundamental processes involved can lead to progress in the modeled land‐atmosphere continuum.

The ability of plants to regulate atmospheric perturbations under a wide range of atmospheric convective situations indicates that a dynamic relationship exists between plants and the atmospheric boundary layer. This relationship stabilizes the plant‐atmosphere system and, in structured convective atmospheres (i.e., from cells to rolls), is capable of locking vegetation patterns together with atmospheric convective conditions.”

For additional research, please see the Science Primary Literature Database.

Questions? Please let me know (engelk@grinnell.edu).

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