Why do those glaciers form on the lee side of the mountains?

Question

In the Scandinavian mountains, there is a strong effect of orographic precipitation. The west receives far more precipitation than the east. This difference can be a factor 5 or more in some places.

But when I observe the locations of glaciers, they seem to be mostly on the eastern side. An example can be found by studying the Norwegian topographic map near Narvik. Almost all the glaciers, on Rienatčohkka, Storsteinsfjellet, Ristačohkka, and others, are on the east side of the mountains, while the west side is mostly bare. If the precipitation is orographic, shouldn't it fall on the west side? Then why is the east side more glaciated? Is this a typical effect, or is there a strange situation locally?

Answer 1

The key is with wind-drifting. The predominant westerlies cause snow to drift into protected places. We should perhaps recall that glaciers exist because they are essentially snow-catchers in a landscape that is sufficiently suitable for some of the snow to survive the summer melt period. The drifting and depositing of snow on the eastern side of mountains thus favours formation of glaciers in such locations. If you take a trip using Google Earth into the Swedish mountains to the East of the area you describe you will see that glaciers are also in north and south-trending valleys where of course they catch snow for the same reason. In this case it is the larger scale geomorphology that dictates the location and direction of glaciers. The latter implies that a glacier is not just formed in the lee direction of the predominant wind direction but also requires a suitable landscape geomorphology which affects the location of where the glacier forms.

Answer 2

Assuming that your observation hasn't mistakenly included temporary snowfields, glaciers, like other forms of water, will take the path of least resistance and will certainly be directed by local geology. Weak strata, faulting type and orientation, and jointing all work to dictate erosional patterns up to the point that they erase them entirely.

I suspect that your observation of "glaciers" only on the east side of these mountains is merely an artifact of (very) local geological structure. In fact, based on this recently constructed glacier flow map of southern Norway 13,000 YBP, one would be hard pressed to claim an overall preferential pattern of glacier position and movement.