I have seen gap flows mentioned in the literature, for example [Gohm et al. 2004, Zängl 2002, Mayr et al. 2007]. Whiteman 2000 defines a gap as a "major erosional opening through mountain ranges" and states that a channel can occur "between mountain ranges". He goes on to discuss pressure-driven channelling and forced channelling. I assume that such flows can occur through an gap but might be more obvious (and more easily observed) in elongated channels.

Can anyone help clarify the distinctions between gaps, channels, passes and valleys and if there are distinctions between the flows associated with these types of terrain.


  • Gohm, A., Zängl, G., & Mayr, G. J. (2004). South foehn in the Wipp Valley on 24 October 1999 (MAP IOP 10): Verification of high-resolution numerical simulations with observations. Monthly weather review, 132, 78-102.
  • Mayr, G. J., Armi, L., Gohm, A., Zängl, G., Durran, D. R., Flamant, C., ... & Weissmann, M. (2007). Gap flows: results from the Mesoscale Alpine Programme. Quarterly Journal of the Royal Meteorological Society, 133, 881-896.
  • Whiteman, C. D. (2000). Mountain meteorology: fundamentals and applications. Oxford University Press.
  • Zängl, G. (2002). Stratified flow over a mountain with a gap: Linear theory and numerical simulations. Quarterly Journal of the Royal Meteorological Society, 128, 927-949.


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