Westerly winds prevail between 35-60° latitude, dominating southern Australia and New Zealand, for instance (Figure 12.1). The winds are powerful across the southern oceans at all longitudes. They show none of the steadiness of the Trades, since they contain rapidly moving and evolving low-pressure systems (or lows— see Chapter 13), around which winds circulate.
Midlatitude westerlies blow over 24 per cent of each hemisphere, whereas the low-latitude (easterly) Trades affect about 31 per cent. These contrary winds impose frictional forces on the ground, which are opposite in direction and more or less equal after allowing for the winds' strengths and also the areas involved. The result is that the atmosphere as a whole is neither
slowed down by the Earth's rotation nor accelerated by it, but turns with it.
Was this article helpful?