© Rayann ElzeinRed auroras on March 10, 2021 @ Utsjoki, Finnish Lapland
Rayann Elzein sends this picture from Utsjoki in the Finnish Lapland. "The red auroras looked pale white to my unaided eye, but a quick exposure with my camera revealed their true color."
What's so tricky about red? The action, if you can call it that, takes place more than 150 km above Earth's surface. At that high altitude, oxygen atoms excited by solar wind slowly spit out red photons. Emphasis on slowly. The radiative lifetime of the transition is 110 seconds--an eternity at the quantum scale. The atoms must remain undisturbed that long to produce their red light.
Perhaps that's why red auroras often appear when conditions are quiet. "The solar wind speed last night was quite low and there was no expectation of a geomagnetic storm," says Elzein. Tonight is expected to be quiet as well. Red auroras, anyone?
Comment: In October last year the same Arctic photographer captured red auroras over Utsjoki, Finland saying, "Rarely have I seen anything like this before."
With the surge in sightings of rare or novel atmospheric phenomena in recent years it seems the electrical nature of our weather and changing atmosphere is becoming more apparent: