Intermittent patches of turbulence generally refer to a small region of significant turbulent eddies often separated by larger regions of very weak turbulence such as fine-scale turbulence. Here turbulent patches includes narrow event like motions as in the ejection in the above photo and include wider groups of eddies as in the video at the bottom of the page. Although patches may occupy only a small fraction of the total area, they can dominate the flux between the atmosphere and ground surface.
Downward bursting of turbulence, generated at higher levels and transported downward, can lead to patches of turbulence near the surface. This downward bursting brings warmer air and higher momentum to the surface. The following video shows an example of a turbulent patch that seems to develop from the surface, which might be an illusion because the fog is surface based. Isolated upward transport is sometimes referred to as ejections.
Often mixing events are associated with a reversal or change of wind direction. The turbulence may be most intense when the wind speed reaches a temporary minimum as in the two videos below. The patches of turbulence in the two videos below seem to be part of a longer semi-periodic change of wind . Recall that the video is sped up eight times so that the turbulent motions are substantially slower than they appear.
Turbulence and Local Circulations 