Editing Planetary boundary layer (section)

===Stably stratified planetary boundary layer (SBL)===
[[File:Interactions-between-the-carbon-green-water-blue-and-heat-red-cycles-in-the-coupled-landABL-system.png|thumb|281x281px|Interactions between the carbon (green), water (blue) and heat (red) cycles in the coupled land–ABL system. As the atmospheric boundary layer decreases in height due to subsidence, it experiences an increase in temperature, a reduction in moisture, and a depletion of {{CO2}}. This implies a reaction of the land surface ecosystem that will evapotranspire (evaporation from the soil and transpiration from plants) more, to compensate for this loss of moisture in the lower layer, but gradually causing a drying of the soil. (Source: Combe, M., Vilà-Guerau de Arellano, J., Ouwersloot, H. G., Jacobs, C. M. J., and Peters, W.: Two perspectives on the coupled carbon, water and energy exchange in the planetary boundary layer, Biogeosciences, 12, 103–123, .<nowiki>https://doi.org/10.5194/bg-12-103-2015</nowiki>, 2015)]]
The SBL is a PBL when negative buoyancy flux at the surface damps the turbulence; see [[Convective inhibition]]. An SBL is solely driven by the wind shear turbulence and hence the SBL cannot exist without the free atmosphere wind. An SBL is typical in nighttime at all locations and even in daytime in places where the Earth's surface is colder than the air above (i.e. an inversion). An SBL plays a particularly important role in high latitudes where it is often prolonged (days to months), resulting in very cold air temperatures.

Physical laws and equations of motion, which govern the planetary boundary layer dynamics and microphysics, are strongly non-linear and considerably influenced by properties of the Earth's surface and evolution of processes in the free atmosphere. To deal with this complexity, the whole array of [[turbulence models|turbulence modelling]] has been proposed. However, they are often not accurate enough to meet practical requirements. Significant improvements are expected from application of a [[large eddy simulation]] technique to problems related to the PBL.

Perhaps the most important processes,{{Clarify|reason = it is unclear what they would be most important for, and what causes them to be most important for it; is the next clause meant as a '''defining''' relative clause (in which case no comma would be expected)?|date=July 2020}} which are critically dependent on the correct representation of the PBL in the atmospheric models ([[Atmospheric Model Intercomparison Project]]), are turbulent transport of moisture ([[evapotranspiration]]) and pollutants ([[Air pollution|air pollutants]]). [[Cloud]]s in the boundary layer influence [[trade wind]]s, the [[hydrological cycle]], and energy exchange.