The first footprints show which journeys could not wait for better conditions.

Before dawn in bad weather, the tracks that exist belong to people with no option. Night shifts, early cleaning, care work, deliveries and hospital rounds go out regardless of what has fallen. Those journeys are usually the least visible in daylight and the least likely to be described as a choice.

Next time conditions are poor, notice who is already out and what work that implies. It is a useful correction to the idea that being somewhere on time is mostly a matter of personal discipline.