Atmosphere synoptic scale motion

The atmospheric boundary layer (ABL) is that portion of the atmosphere where surface drag due to the motion of the air relative to the ground modifies synoptic-scale motions caused by horizontal pressure gradients, Coriolis forces, and buoyancy. The depth of the ABL is highly variable (50 to 2000 m), but it generally increases with proximity to the equator, with wind speed, and as the earth surface roughness, but it decreases... 

Order of Magnitude of Atmospheric Quantities It is useful to estimate the order of magnitude of quantities in the equations of motion on the synoptic scale (systems having a spatial scale of 1000 km). Typical orders of magnitude of quantities are as follows (Mcllveen 1992) ... 

Synoptic scale Scale of atmospheric motion with horizontal length scale greater tlm 2000 km and time scale longer than 24 hr. 

This field is almost always in a state of change and is characterised by a spectrum of atmospheric motions ranging from micro-scale eddies, through meso-scale to synoptic-scale circulations. The elements of the field critical to pollutant transport are wind speed and wind direction. 

The motions on the largest spatial scales amount to the aggregate of the world s synoptic weather systems, often called the general circulation. Both with respect to substances that have atmospheric lifetimes of a day or more and with regard to the advection of water, it is useful to depict the nature of this general circulation. The mean circulation is described to some extent in terms of the Hadley and Ferrell cells shown in Fig. 7-4. They describe a coupled circulation... 

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