text: Rain is generally preceded by a drop in the barometric pressure, right? That's why your old scars or bad knees or whatever ache when rain is coming. Your body is adjusting to the drop in pressure.\n\nSo the idea is that maybe the lower pressure affects a cow's digestive system - all those gasses and juices and stuff in all those stomachs.\n\nSo this kind of puts the cow off its feed, and it doesn't feel like grazing.\n\nBeing a cow and all, it can't think of anything else to do so it lies down.