Contrasts

The effect of the Hadley cell on regional climate is explored, in particular the dry subtropical regions where many of the world’s deserts are to be found, and the equatorial region frequented by deluges and floods. Some effects of friction in fluid dynamics are considered, which explain the rich fishing waters off the west African coast. Our discussion of the key balances in atmospheric fluid dynamics is completed, with links to the flow of energy through the atmosphere and oceans. The chapter concludes with the example of the North African Sahel, a region where dramatic swings in climate have had severe impacts on humanity.