I know we are over thinking this, and halo itself is not a bastion of scientific plausibility and groundedness. But for the sake of talking about the idea of a halo ring weather for the sheer sake of it, I think it would need to have wind currents, even if extra care is necessary to artificially create them. If they are trying to house different life forms of animals, plant life and so on, I'd assume wind is a necessity. It plays key roles in polinization, and the cycle of water. Without wind, water that evaporates would rain back excatly on the same spot it evaporated from. Also, without wind, there would not be temperature changes large enough to give you rainy days/vs sunny day. Every day would have the exact same weather pattern, and rain fall would be affected only by time of day. Certain biomes might probably just become a lifeless desert, and others would become a soggy constabtly misty swamp.
Then, there are also the seasons, which I think are a key regulator of behaviour on so many lifeforms, that it would be essential to be recreated too to make life viable at all.
). Basically like a greenhouse, just on a really massive scale.
