Physical processes causing the formation of penitentes

TL;DR

This paper investigates the physical mechanisms behind the initial formation of snow penitentes, emphasizing vapor diffusion and heat conduction over self-illumination, and derives the characteristic wavelength of these patterns.

Contribution

It provides a linear stability analysis showing that penitente formation is mainly driven by vapor diffusion and heat conduction, not self-illumination, and derives the characteristic wavelength.

Findings

Penitente patterns are controlled by vapor diffusion and heat conduction.

The characteristic wavelength depends on aerodynamic vapor mixing.

Self-illumination is not the primary factor in penitente formation.

Abstract

Snow penitentes form in sublimation conditions by differential ablation. Here we investigate the physical processes at the initial stage of penitente growth and perform the linear stability analysis of a flat surface submitted to the solar heat flux. We show that these patterns do not simply result from the self-illumination of the surface --a scale-free process-- but are primarily controlled by vapor diffusion and heat conduction. The wavelength at which snow penitentes emerge is derived and discussed. We found that it is controlled by aerodynamic mixing of vapor above the ice surface.