Zonda (or Sondo)

Location: Argentina, South America

The Zonda is a hot wind of foehn type on the eastern slopes of the Andes in central Argentina. The name seems to apply to two winds of quite different origin.

(a)   The most common use is for a dry foehn wind descending the eastern slopes of the Andes in the central Argentine in winter, probably polar maritime air warmed by descent from the crest which is some 6,000 m (18,000 ft) above sea level. It may exceed a velocity of 25 mph (40 kph). Like the foehn it sometimes begins with a high foehn (zonda de altura) which overrides a layer of cold air in the lee of the mountains, eventually sweeping it away and descending to ground level as zonda de superficie (or just 'zonda'), but this initial cold air mass is not always present. The zondas carry a lot of dust in the dry season.

(b)   It also describes a hot humid north wind in the Pampas, in advance of a depression moving eastwards, and preceding the pampero. This wind is also called the sondo.