Now you see me, now you don’t.
During the dry season at Botswana’s Makgadikgadi salt pan, temperature inversions lead to all manner of mirages. Credit: Stephen James O’Meara
Any reference will tell you the Novaya Zemlya effect is a polar mirage — and it is. But Novaya Zemlya-like effects are not limited to the Arctic.
The Novaya Zemlya effect is an atmospheric refraction phenomenon that causes a viewer to perceive the premature birth of the Sun as the long polar nights near an end. On Jan. 24, 1597, Gerrit de Veer, a member of Willem Barentsz’s icebound third arctic expedition, became the first known person to record the phenomenon; the Novaya Zemlya effect is named after the archipelago in northwestern Russia where he witnessed it. On that day, two other crew members also glimpsed the Sun two weeks before it was expected to rise.
Further observations by Barentsz and his crew, as well as observations from other artic explorers in later years — including Ernest Shackleton during his 1914–1917 expedition to Antarctica — lent credence to the reality of the phenomenon. But as Siebren Y. van der Werf and colleagues explain in the January 2003 issue of Applied Optics, the sightings met with disbelief from their contemporaries and triggered heated discussion among scientists, including German astronomers Johannes Kepler (1571–1630) and Michael Maestlin (1550–1631). Investigations and atmospheric modeling by van der Werf and others, however, have now placed the truthfulness of these sightings beyond doubt.
Today, Novaya Zemlya-like effects in the form of segmented Suns have been seen well beyond the Arctic: from the Channel Islands off the coast of Normandy, France (49° north latitude); Boston (42° north latitude); Santa Croce Camerina, Sicily, and San Francisco (both 37° north latitude); and even Mount Wilson, California (34° north latitude), to name a few. Apparently, it is possible to observe variations of the Novaya Zemlya effect wherever temperature variations are just right to produce strong atmospheric refraction over large, flat areas of Earth’s surface. It’s now common to refer to such effects as either a premature rising or delayed setting of the Sun on a much smaller scale — in a matter of minutes, rather than weeks.
A tropical sighting
On the morning of Aug. 9, 2023, a group of friends and I had the opportunity to witness a tropical Novaya Zemlya-like effect from the Makgadikgadi Pans in Botswana (20° south latitude). This 6,178-square-mile (16,000 square kilometers) salt pan is one of the largest and flattest on the planet. During the dry season, the region’s desert climate can bring a 30-degree Fahrenheit (17 degrees Celsius) or more difference between day and night, making it prone to strong temperature inversions, which occur on clear nights when the ground cools off rapidly by radiation.
After sleeping out under the stars, we grouped together that morning to wait for a possible green flash. Around 6:40 a.m., with Earth’s shadow still visible in the western sky, I was surprised to see a bead of light from the upper rim of the Sun already manifesting just over the eastern horizon. As the Sun normally makes its appearance in the east when Earth’s shadow sets in the west, I knew something was askew.
Indeed, the Sun was still about 2° below the horizon when we first glimpsed that bead of light, which vanished about 15 seconds later — only to reappear some 30 seconds later as three beads strung out along the horizon (two close together, and one father south). Once again, the beads vanished, only to return this time as a long, flat ribbon of light before it too blinked out. The flat lid of the Sun soon made a second showing, when it swelled slightly into a flattened rectangle. Then, over the course of a minute or two, this flattened form slithered northward along the horizon until 6:45 a.m. (the predicted time of sunrise), when the rest of the Sun began rising.
If you have witnessed a similar phenomenon beyond the Artic, send reports to sjomeara31@gmail.com.