Of all the headaches I've experienced when trying to image at a remote site, wind has caused about 50% of them. For the last few outings, I've used my own version of what is essentially a Sky Box design pioneered by John Love. It held up very nicely in strong Nevada and Colorado winds, but I could tell that my scope was still being affected by some turbulence inside the box. I'm about the same height as my rig, and my hair was getting blown around a little bit. Making the box taller was an obvious solution but it came at a cost of viewing (imaging) angles.
My scope is just below the top of the box.
There have been several threads on wind breaks, but none permit any definitive conclusions on the best way to deal with wind at imaging sites:
The Sky Box seemed to be the best option, so that's what I tried first. But I knew that some of the other ideas - particularly about mesh screens - warranted some testing.
If you can't tell from the photo above, a solid tarp takes a beating in the wind. The windward face experiences enormous pressure and even subtle changes in wind direction cause thunderous flapping of the tarp. I wondered if putting a 70% mesh wall in front would help, so I set up a little experiment:
All wind speeds are 15 second averages.
I set up an anemometer downwind of a large fan. I drilled holes to experiment with wind break placement (and material). Fully exposed, the wind speed at the anemometer (telescope) position was 8.2 mph.
The first thing I tried was my standard "Sky Box" setup - solid tarp walls rising just above the top of the anemometer.
The wind speed at the telescope position was 1.1 mph. Not bad at all, and I suspect that for most people that a ~90% reduction in wind speed is a completely satisfactory result. But I need to remember that my wind break will see 20-30 mph gusts, which would put the wind speed at my scope around 2.5 to 4 mph. And that's to say nothing of the worrisome strain on the structure itself. So if you image in more extreme environments and/or are just one for overkill, read on.
After trying various material combinations and layouts, I landed on the winner: a solid tarp box with a wall height just over the height of the telescope (to maximize visibility), with a large 70% mesh wall about 6 feet in front (the windward side).
The scale of my model is such that 1 inch = 1 foot in real life. In this hypothetical setup, the tarp box measured 10' x 10' x7' (the telescope height being 6.5'), the mesh wall was 6' in front of the box and measured 14' wide x 10' tall. I know, that's huge. But it reduced the wind speed at the telescope position to zero. When I reduced the height of the mesh wall to 8', I had to bring it 4' closer (so 2' in front of) the box and it was almost as good with a reading of .2 mph.
The leading mesh wall is obviously overkill for most people but it accomplishes two objectives: (1) it eliminates wind at the telescope position while preserving good visibility, and (2) it dramatically reduces the strain on the tarp box structure and (hopefully) will quiet the "thunder flap" effect when winds change direction.
With the mesh wall 6' in front, the wind speed in front of the box was 0 mph - keep in mind, that's down from 8.2 mph.
With the mesh wall extending 2' beyond the width of the box, the wind speed on the side of the box was 1.5 mph.
Other interesting things I learned:
1. 70% mesh on it's own is actually surprisingly effective.
2. Leaving a 6" gap at the floor of the tarp box made no measurable difference on the wind speed at the telescope position.
Hope this helps. I'll update with full scale results the next time I'm in the field.