Westerlies

The west wind zone, West Wind West Wind Drift designated location or an atmospheric air circulation in the middle latitudes of the Earth, ie approximately between 40 ° and 60 ° on the northern and the southern hemisphere. Partly can also reach 70 ° latitude the flow. It runs from west to east and is part of the planetary circulation.

In contrast to other global wind currents such as the Passat circulation prevail in the west wind zone both on the ground and in the height of the troposphere winds from the west, but the wind conditions are relatively uniform. The transported air masses are thermally temperate and relatively humid.

The instability of the West Wind Drift is to establish in the overlay through the polar front that arises between warmer, suptropisch influenced air masses and cold polar air, thereby forming Rossby waves. The resulting cyclogenesis and relocation of low-pressure areas in the west wind drift also leads to disturbances. Other variations result from the seasonal insolation differences, so that the west wind drift is less pronounced in summer than in winter. Above the polar front in the area of the west wind zone in the height a narrow strong wind field, the jet stream.

The west wind drift is more pronounced in the southern hemisphere where it drives the Circumpolar Current. This powerful oceanic flow is it that is meant in English with west wind drift. Wind - and water flow are the reason why sailing ships as the earth can drive around in the opposite direction faster and easier in west-east direction. For example, the tall ships from Europe, Australia and New Zealand ran mostly on the route around the southern tip of South Africa around, whereas the return to the southern tip of South America was. See also the modern Vendée Globe.

Similar effects does the west wind zone on the aviation sector. A typical example is the non-stop flight of a jet plane in 10-12 km altitude: On the way from Europe to America to the west meets the frontal plane to up to 400 km / h fast jet stream, which correspondingly reduce the ground speed depending on the lead angle. On the return flight, however, the aircraft can be accelerated above ground in accordance with vigorous tailwind to over 1000 km / h. This may result in flight time differences of more than one hour.