I'd like to share an unusual (to me) experience.
We had the last day of our winter series yesterday and the wind picked up with a passing cold front. (From zero to ten knots, it looked like a step function on the weather station's graph). The wind was a bit shifty and gusty, but as long as we were on the water not so strong as to be overpowering.
Now to the unusual part.
Normally, when the crew tells me that a gust is about to hit, I would get ready to luff up a bit, perhaps even anticipating the blow a bit, that seems to make it less sudden and then the boat heels and accelerates. Now, yesterday, every time I tried that, the boat would stand up and slow down.
Looks like the wind would shift direction with each gust, so it would come in more from the side than forward, so I had to fall off to stay in the wind. This was not a fluke, but a consistent pattern (the course was skewed so we sailed mostly on one tack and not the other; so I didn't have as much of an occasion to observe whether there was anything unusual there).
So, what was going on?
Normally, when a gust hits, the ratio between boat and true wind-speed changes. The effect of boat speed on the apparent wind becomes less. That makes the apparent wind move back. So the response is to luff up, because close-hauled is now closer to the true wind direction. That effect should be the same on either tack, and hold true as long as the direction of the wind and the direction of the gusts are the same.
Now, gusts are supposed to be an effect of turbulent air flow, where an eddy of faster air moves down to the water. Gusts that are caused by descending air will "splay out" on the water, and the fringes of the gust will have somewhat different direction (with a component away from the middle). However, as I'm sailing through a series of gusts, I would not expect to be on the same side of all of them. As we observed a consistent pattern, something else must be happening.
When I looked at weather station graph afterwards, I noticed that during the entire time, the wind was steadily and continuously shifting (about 90 degrees in an hour). Best I can puzzle it out is that at any time, the wind aloft was blowing further in the new direction, and each time a gust descended, it brought that direction with it.
As a result, we were headed (and de-powered) in each gust, until we clued in and anticipated that effect.
Now, for the opposite tack, this should have resulted in an extra lift on each gust. As one expects to be lifted a bit in a gust anyway, it's perhaps not as easy to spot the effect, and not as memorable, and I don't recall anything unusual.
Anyway, for me, it's the first time that I've seen this effect. It would, of course, be linked to the passing of that front, but to show up like that it would seem to require that steady change in wind direction. If it was due simply to wind shear based, for example, on the Coriolis effect (faster air affected differently than slower air) I'd think it would show up all the time.