For an axisymmetric ring of air advected poleward at upper levels within the Hadley circulation, conservation of absolute angular momentum (M = Omega x a^2 x cos^2(phi) + u x a x cos(phi), where Omega is Earth's rotation rate, a is Earth's radius, phi is latitude, and u is the relative zonal wind) can be used to derive the zonal wind the ring acquires as it moves to latitude phi, assuming the ring starts with zero relative (zonal) wind at the equator and that angular momentum is conserved with negligible friction at upper levels.