The Ferrel cell is usually shown between the Hadley and Polar cells, e.g. atmospheric circulation. It is named after William Ferrel, who was concerned with describing the surface flow in the Temperate zone of air that came from the Horse Latitudes, namely the Westerlies. In the region of the Atlantic ocean the Westerlies are the northern part of the general circulation of air about the high pressure system that sits over the Horse latitudes. The main 'problem' with the Ferrel cell is that it is thermally indirect.
However, the true atmospheric circulation is rather more complex than the simplified zonal mean pictures would lead one to suspect... It is possible to argue that the Ferrel cell does not exist.
References
- Laing, David (1991). The Earth System: An Introduction to Earth Science Wm. C. Brown ISBN 0-697-07952-X