I wonder how much is functional vs. esthetic design for some of these.
Yet this must get the attention of some, since airports may have those little loin cloth like things hanging around their rain gauge installations to mitigate side winds. Not sure what they are called but a sort of circle wire suspending panels of metal all a few feet in diameter.
In addition, if you look at the RM Young capacitive gauge, the 50202
http://www.youngusa.com/products/3/17.htmlit has a complex upper portion, although it seems mainly to give a knife edge to the collecting lip and then perhaps just functional on the way down to house the innards.
I can't imagine someone at Young didn't think of the impact on collection that wind would have.
Yet I think that unless you are concerned about the fine mist that seems to be easily disturbed by light drafts, that any impact of the air above the lip would have much impact on the diversion of drops away from the collector.
I wonder if you could get one of those things that makes smoke and see how the air flow around a few of these might play out on a still day with some fans running at a slight distance to give as good of a wind tunnel as you can get without being NASA or NOAA? I am amazed at the ground effect (air plane term) and when the car advertisers want to show how aerodynamic their car shapes are, the smoke never touches the car, but stays a few inches away as the boundary layer deflects it.
I'll stop rattling but wanted to mention an interesting car I had, an old Toyota hatchback we got as our first ever new car right after we were married. That thing would seldom need windshield wipers when you were going over 45 mph for most snow and a lot of light rain, and the hatchback would also stay darn clear of snow build up on the way down the road.
It was a noticable effect and never had another car that did that type of precip clearing.
How do they make those smoke columns on those wind tunnel tests, anyway? Some huge cigarette behind the scenes? A nice incense punk? Just curious.