But Tom, according to your model, the air would flow towards the ice wall, and continue to move past the ice wall. It wouldn't just stay there...the point is the system would be losing air.
As the system loses air it also gains air from the currents which originate from the Ice Wall. There must be a balance; the equator cannot deplete it's air reserves because the temperature of the environment demands that the equator have a certain set pressure.
Therefore; as the equator looses pressure from high moving into low in one area the equator also takes some excess pressure from the poles in another area.
The system never gains or looses air; there is a perpetual cycle which constantly replenishes the equator and poles.
Questions:
If air is always moving from the equator (high pressure) to the North Pole (low pressure), why doesn't the equator deplete itself into the North Pole and the two areas equalize?
Why are there air currents which originate from a low pressure environment (North Pole) into a high pressure environment (North America, Europe) ?
I have a feeling I won't be able to convince you of this, but the Earth's atmosphere cannot be considered a closed system, like a sealed canister would. There is too much space and no physical barrier for the pressure to push against. Not to mention the fact that the atmosphere's composition is constantly changing due to photosynthesis, respiration and many industrial processes.
Air is always moving, but that doesn't necessarily mean from the equator to the poles. The relative differences in pressure between the poles and the equator is partly due to temperature differences but also largely due to physical processes affecting the earth due to its spinning. In the 1700s, the French Academy of Sciences dispatched two expeditions. One expedition under Pierre Louis Maupertuis (1736-37) was sent to Lapland (as far North as possible). The second mission under Pierre Bouguer was sent to what is modern-day Ecuador, near the equator (1735-44). The purpose of this mission was to measuring, for a number of points on earth, the relationship between their distance (in north-south direction) and the angles between their astronomical verticals (the projection of the vertical direction on the sky). The result of these measurements was the conclusion that the earth is not in fact spherical but oblong in shape due to the speed at which it spins and the centrifugal forces it is subjected to. To this end, the atmosphere is affected in the same way, possibly to a higher degree due to its fluid nature. The constant spinning of the earth causes the atmosphere to collect (on relative terms) along the equator, thus causing overall higher pressure (also due to the higher temperature but we'll get to that in a second). This same force causes the atmosphere to be less dense at the poles. The reason the overall pressure differences stay this way is because the centrifugal force is great enough to overcome the overall tendency for air to move from high to low pressure environments.
However, in the troposphere especially, there is still enough variation in temperature and air pressure to cause air movement. Another reason that the atmosphere does not displace itself to the poles and stay there is because there are relatively low and high pressures within both the poles and the equator that allow for movement in both directions. As the air is heated along the equator, it rises due to it's decrease in density. As this warm air rushes up into the atmosphere, a low pressure area is left along the surface. Cooler air from the surrounding areas rushes to the equator to fill this low pressure area, becomes heated, rises and continues the cycle. The same is true for the poles. The warmer air in the upper atmosphere begins to cool and condense. This causes it to fall toward the surface. The increase in pressure from this cooler air falling forces the air on the surface away and thus creates the arctic winds that cool us so much in North America. Those winds continue to warmer areas, gain energy, rise up and once again continue the same cycle.
The earth's atmosphere is constantly trying to equalize itself but it is influenced by so many factors (solar radiation, human activity, photosynthesis) that it can never happen. I have just fully explained one of the main driving forces of Earth's weather (the other is moisture differences). The problem that you are faced with, as FE believers, is that for weather to exist on the scale that it does and in the way that it does requires a round earth that allows the free flow of atmosphere in ALL directions.