The pattern of surface winds on an ideal non-rotating uniform Earth would be related to the distribution of surface temperatures. This would lead to atmospheric pressure gradients which, in turn, would produce surface winds. The effect of the Earth's rotation produces the so-called ‘Planetary Wind System’, and the actual pattern of surface winds is often considered to be a modification of this. But many factors influence the global wind system to such an extent that the explanation of any part of the system at any given time is a matter of considerable complexity. Moreover, experience has amply demonstrated that despite the close attention of physicists the accurate forecasting of winds for more than a day or so ahead has not met with hoped-for success.