Planetary boundary layer

This movie is a combined visualization of the PBL and wind dynamics over the Los Angeles basin for a one-month period. Vertical motion of the PBL is represented by the gray "blanket". The height of the PBL is largely driven by convection associated with the changing surface temperature of the Earth (for example, rising during the day and sinking at night). The colored arrows represent the strength and direction of winds at different altitudes.
Depiction of where the planetary boundary layer lies on a sunny day.

In meteorology, the planetary boundary layer (PBL), also known as the atmospheric boundary layer (ABL) or peplosphere, is the lowest part of the atmosphere and its behaviour is directly influenced by its contact with a planetary surface.[1] On Earth it usually responds to changes in surface radiative forcing in an hour or less. In this layer physical quantities such as flow velocity, temperature, and moisture display rapid fluctuations (turbulence) and vertical mixing is strong. Above the PBL is the "free atmosphere",[2] where the wind is approximately geostrophic (parallel to the isobars),[3] while within the PBL the wind is affected by surface drag and turns across the isobars (see Ekman layer for more detail).

  1. ^ "Planetary boundary layer | atmospheric science | Britannica". www.britannica.com. Retrieved 28 June 2020.
  2. ^ "Free atmosphere". glossary.ametsoc.org. Retrieved 21 March 2021.
  3. ^ "Geostrophic wind level". glossary.ametsoc.org. Retrieved 20 September 2018.

Planetary boundary layer

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