Gusts are essentially higher speed upper level air pushing down into the surface layer. It can form cells which may not themselves move anywhere near as fast as the wind in them.
As AA says, it is all about instability.
It is a little more complicated.
This is a good summary of some of the factors.
http://www.dwc.knaw.nl/DL/publications/PU00018870.pdf
As mentioned earlier, sailors will be familiar with headers and lifts when sailing and especially racing, however, I would expect the pattern they leave to be different, and with which you would be familiar if accustom to racing around the bouys.
Whilst different again, the remenants of ships passing, especially in relatively shallow water (and I would include in that areas such as the solent), can be very pronounced from the air. It is extraordinary how much detritus large ships can churn and how long their wakes remain (hours after the ship has passed). I have some good photos of just this in the solent from a few thousand feet. The same is true mid channel where the passage of ships in the east and west bound lanes can leave wakes that remain for a very long time, often caused by mixing water at lower depths with the surface layer. Of course the more carm the sea, the more pronounced these effects.
