There are two main types of snow compass: those formed by wind and those formed by sun. Here we will look at snow compasses created by the sun, or more specifically, by the sun’s shadow.
The sun rises in the morning and sets in the evening. It is highest as it crosses your meridian (the line that runs from the North Pole between your feet to the South Pole) and this is when it is giving us most of its heat, light and energy.
The middle of the day is also when the sun does most of its drying and thawing. This is why we can use puddles to navigate.
In mid to high latitudes the sun is low for most of the day in winter and only rises high enough to thaw snow or ice near the middle of the day. This creates dependable ‘snow shadow’ compasses.
They stretch from the thing that casts the shadow towards the north. Their exactly alignment is unlikely to be a perfect South-North line because it will depend on the timing of the thaw, but it is likely to be consistent over a wide area.
The Snow Shadow compass can be created by hundreds of different objects in towns or the wild. These photos I took during a recent visit to Banff in Canada show a typical selection.
For more examples see the blog posts:
Snow Wonders about navigating in snow.
I saw a rather nice example of the snow shadow compass on some molehills in West Sussex recently. Can you tell which way we are looking? Answer below.
The southern sun has melted the snow on the left of the molehills. We are looking West.