this descending subtropical air spreads along earth's surface both back towards the equator (these are the trade winds, between 0-30° N or S) and also to higher latitudes (westerly wind belts, 30-60° N or S)
the westerlies rise over the dense cold air moving away from the polar high-pressure caps (the polar easterly wind belts) -- they rise at a subpolar low pressure belt located at 60°
the air that rises at 60° latitude cools by releasing water vapor and then descends in the polar regions or the subtropics