A recent paper by Claudin and others (2015) expands nicely on previous understanding to provide a pretty comprehensive explanation of the physics of the growth of snow and ice penitentes, pictured below.
The nub of it is that Claudin and others (2015) provide a full suite of equations describing the formation of penitentes. In addition to previously developed ideas of radiative control on the developing relief in penitente fields, this study adds the important role that is played by sub-surface melting and temperature gradients within the penitente structures, and also introduces a length scale, related to the vertical structure of the humidity above the penitente field, that controls the spacing of the penitentes. Great stuff!
My hydrologist colleague Simon Gascoin, who has previously also worked in the semi-arid Andes of Chile just put me on to the fact that the online newspaper ‘Physics‘ from the American Physical Society has produced a focus article describing the new features and the relevance of the Claudin and others paper. As the writer Philip Ball has done such a nice job, I won’t write my own piece on this paper but simply provide the link to his article here: http://physics.aps.org/