And don't forget that all HID lights put out IR.
Within distances of 6 inches or closer, the IR may fry your plants.
Wind has no effect on IR.
I imagine if one were to replace the glass with glass that is rated at the absolute best clarity and had an IR filter applied on it or in it, it might let you put the light even closer.
I use a 430 watt HPS at 8 inches and everything is good with fans blowing on the lights. I've tried 6-7 inches in the same conditions and it started frying the leaves on the top.
I'm saving for some air-cooled reflectors. I need 6 of them so the cost is a chunk from my current budget.