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 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, 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 pollutants). Clouds in the boundary layer influence trade winds, the hydrological cycle, and energy exchange. See also Aeroplankton Boundary layer Ekman layer Mixed layer Alpine planetary boundary layer Turbulence Wind shear Microburst Atmospheric physics Atmospheric sciences Atmospheric electricity Astronomical seeing Remote sensing atmospheric boundary layer Representations of the atmospheric boundary layer in global climate models Atmospheric dispersion modeling References External links Description of the planetary boundary layer at theweatherprediction.com American Meteorological Society glossary entry Boundary layer meteorology Articles containing video clips fr:Couche limite#Météorologie