I am having trouble with the notion that pressure is applied to all sides uniformly. It seems to contradict with my understanding of why there is a pressure gradient in the atmosphere. The way I understood it, the reason you experience more pressure at lower altitudes, is because the parcel of air right on top of you experiences more pressure because there is a lot of air on top of it. But if pressure is exerted on all sides, then the parcel of air above you exerts the same pressure on the air above it as it does on you. Wouldn't that mean there is no pressure gradient?