© Janey Thomas

Woolshed Hill (1 429 m), Arthur’s Pass National Park, New Zealand

Latitude: 42° 57' 57'' S

Longitude: 171° 46' 35'' E

13 January 2014 1420 (Local Time)
Camera direction: towards NNW

Image P/S code: P.25.5

Image I.D.: 6078

• Images & related info Other Images Images of 1987 edition
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  Foehn wall

  The foehn wall is a cloud formation which, during an episode of foehn winds, lies over and along a mountain ridge and which appears to an observer downwind from the ridge as a wall or bank of cloud. 

  This picture shows an example of the foehn wall over the Southern Alps of New Zealand. The Southern Alps is a mountain range that extends for approximately 500 km, south-west to north-east, along much of the length of New Zealand's South Island. With several peaks at heights of over 3 000 m above sea level, it forms a major barrier roughly perpendicular to the prevailing westerly airflow. Air rising over the mountains cools, forming cloud and precipitation on the western side, whilst air descending on the lee side gives a warm, dry foehn wind. The foehn wall marks the eastern limit of the cloud that exists over the windward, western side of the mountain range.

  Links in the image description will highlight features on the image. Mouse over the features for more detail.

  © Janey Thomas
  Woolshed Hill (1 429 m), Arthur’s Pass National Park, New Zealand
  Latitude: 42° 57' 57'' S
  Longitude: 171° 46' 35'' E
  13 January 2014 1420 (Local Time)
  
  
  Camera direction: towards NNW
  Image P/S code: P.25.5
  Image I.D.: 6078
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  Foehn wall and drifting dust

  This picture was taken from a location in Argentina to the east of the Andes mountain range during a foehn wind event. There are two main features in the image:

  1) The large band of cloud over the mountains is known as a foehn wall. The foehn wall is a cloud formation which, during an episode of foehn winds, lies over and along a mountain ridge and which appears to an observer downwind from the mountains as a wall or bank of cloud. The foehn wall marks the eastern limit of the cloud that exists over the windward side of the mountain range.

  2) The warm, dry downslope foehn wind (known locally in Argentina as the Zonda wind) is strong enough here to raise dust to a small height above the ground. This is known as drifting dust.

  Links in the image description will highlight features on the image. Mouse over the features for more detail.

  © Maximiliano Viale
  Bardas Blancas, Mendoza, Argentina
  Latitude: 35° 56' 24'' S
  Longitude: 69° 44' 24'' W
  31 October 2016 1224 (Local Time)
  
  
  Camera direction: towards NW
  Image P/S code: S.12.2.1.1
  Image I.D.: 6082