The spreading out of an air mass into paths of different directions, linked with the vertical shrinking of the atmosphere (see R. Barry and R. Chorley (1992) fig. 3.6). Upper-air divergence is associated with ground level depressions (Sutcliffe and Forsdyke (1950) Quart. J. RMS 76, 328), and closely related to vertical vorticity; see Chen and Bosart (1979) J. Atmos. Scis 36, 2.
Subjects: Earth Sciences and Geography.