I just noticed that in our paper in which we presented measurements of the changing surface morphology of penitentes on a glacier in Chile, the main figure which was supposed to use transparencies does not in the final production version. So I thought I’d put this version of how it was supposed to look on here:
The top panels show the hypsometry (area-altitude distribution) of the surface over time (colours shifting from greenish to purple over 25 Nov, 11-Dec, 20-Dec, 03-Jan), by plotting the % distribution of surface elevation showing that while the overall surface lowers, its relief (the vertical spread of the hypsometry) increases.
The second panels show that as the surface lowers, and the relief increases, the penitentes steepen.
The third panels show the aspect distribution of the surface, indicating the strong east-west alignment of the penitentes, and also showing a slight rotation of the alignment over time as the path of the sun alters over the course of the summer.
Nicholson, L. I., Petlicki, M., Partan, B. and Macdonell, S.: 3D surface properties of glacier penitentes over an ablation season , measured using a Microsoft Xbox Kinect, The Cryosphere, 10, 1–31, doi:10.5194/tc-2015-207, 2016.
You can download the paper from the publications page or consider searching these blog postings for ‘penitentes’ to get more information on these crazy snow and ice features.