Abstract
A statistical analysis of the daily displacement and size of cyclones and anticyclones appearing over the Northern Hemisphere for a 2-yr period is described. The longitudinal motion of both types of vortices is inversely proportional to their size. In middle and high latitudes the poleward motion of cyclones is directly proportional to their size. At all latitudes the systems move in the same direction as the vertically averaged zonal wind component but at a slightly lower speed. Significant correlations were found between central pressure and size, and between maximum size and lifetime for both cyclones and anticyclones.