Low on the horizon, the sun casts an eerie light on the icy sea. For several hours, the glow transforms the colorless terrain into shades of pink as the sun does not rise or set, but edges to the side — traveling in a semicircle before slowly sinking one last time.

I am far north in the Arctic Ocean, and polar winter has just begun.

Every year, the North Pole tips away from the sun and the region is plunged into darkness for months, meaning that t he sun will disappear with a final sunset in the fall and reappear with an initial sunrise in the spring. But precisely c alculating these dates is challengin g .

In the Arctic, the air temperature slowly decreases the higher you get above the sea. Then it significantly increases — a temperature inversion that causes a change in air density. That makes light from the sun bend around the horizon, similar to the way your arm appears to bend below water. The result is the sun seeming to hang in the sky even after it has physically dropped below the horizon.

If fluctuating weather allows you to see it. The location and strength of the temperature inversion changes daily — and occasionally hourly — making it difficult to predict when this odd effect will occur.