Actually, if you look at the zonal averages (the average along the parallels) of the wind in the atmosphere, you will find a reverse circulation at mid-latitude. This circulation is called a Ferrel cell. The flow of the atmosphere at the mid-latitudes is characterized by the baroclinic instability, which causes high and low pressure systems. On the other hand, the circulation of air at low latitudes is close to the model that Hadley proposed long ago, so these areas are called Hadley cells.