Wave-like motions are abundant in most of our stable nocturnal boundary layers. Such motions are generally observed at fixed sites with only a few periods. Cases of more than a few periods with roughly constant period and amplitude are uncommon at the ground surface. However, such cases are emphasized in the literature and they do become more common at higher levels above the ground. Our library of several hundred fog videos and our datasets indicate that shallow wave-like motions are quite common particularly at sites over flat terrain. In more complex terrain, the structures are more complex and often include microfronts.
The following video shows examples of wave motions propagating in opposite directions.
The above video shows somewhat larger waves. Note that the depth of the waves may extend well above the fog layer and thus not visualized.
Wave like motions can be identified in the foreground and in the background. Do the near-field and far-field waves appear to be coherent?