When you ask the question "why do we have outdoor lighting" the reason most people come up with first is for safety". But it often happens that lamps actually make vision worse than it would be if it wasn't there, as we've seen on the blog before. Lighting can be especially tricky near staircases.
I'm currently in Montsec, Spain, for the 4th LoNNe Intercomparison Campaign. We are staying in a wonderful hotel in a region that is brightly lit with stars. On the days that the hotel has kept the lamps off for us, this staircase has been easy to climb with adapted eyes under starlight:
But on the first night we were here, it looked like this in the night:
The light flashed through the stairs, and made it very difficult to see. The culprit was this old-timey style lamp mounted near a doorway below:
If the lamp was better shielded so that it didn't shine sideways (and upwards), the guests at the hotel would have a safer and easier trip up to their rooms at night.
The three photos above by Christopher Kyba are licensed under a Creative Commons Attribution 4.0 International License.