Data from the infrared radiometer aboard the Pioneer Venus Orbiter are examined and interpreted within the context of zonally averaged temperatures and circulation in the upper atmosphere of Venus. Surprisingly, the northern hemisphere pole is warmer than the equator throughout most of the region sampled. This implies both a rapid decrease with height of the 100 m/s cloud top winds previously observed, and the probable existence of large (50 to 100 m/s) meriodional winds.