JACKSON, Wyo. — In the winter months, Jackson residents may observe pillars of light beaming up from the ground into the sky. This optical atmospheric phenomenon occurs on frigid winter nights, usually in subzero temperatures when there is high humidity and minimal wind, resulting in the appearance of “light pillars.”
When these freezing and humid conditions are present, tiny (about 0.02 mm) ice crystals will form and remain suspended in the atmosphere near the surface. The suspended ice crystals are great reflectors, beaming city lights back down to the human eyes/camera lens.
Usually, these are plate-shaped ice crystals, which form at temperatures of 14° to -40° Fahrenheit or -10° to -40° Celsius.
Due to the fact that the ice crystals are so small, light pillars can occur without visible clouds in the sky. But, if low-level clouds are present at these frigid temperatures, they will consist of ice crystals and supercooled liquid droplets. These “icy” clouds typically occur at higher levels of the atmosphere, like cirrus clouds.
Experts say that low-level ice-filled clouds can also reflect city lights, like the ones in the Town of Jackson, creating a glow at a night. Pair the low clouds with a fresh blanket of snow, and lights are reflected even more so. According to a 2019 study, “Snowglow” can be twice as bright as a full moon.
