By Marcia Wendorf
On December 20, 2019, Iceland received one of the largest snow storms in its history. The so-called “10-year storm,” brought winds of 100 miles per hour (161 km/h), with one weather station reporting gusts of up to 149 mph (240 km/h).
Sustained winds reached 90 mph (145 km/h) in the Northeast part of the country, and 10 feet (3 m) of snow fell in the North. The storm was so severe that the Icelandic Meteorological Office issued an unprecedented “red alert.”
The snow cyclone caused atmospheric pressure to drop to 944 millibars (mbar) on land, while the average pressure at sea level is usually over 1,000 millibars. Compare that to the 946 millibars that Hurricane Sandy brought with it when it made landfall in New Jersey in 2012.
Iceland’s, Europe’s and North America’s weather has historically been tied to the sunspot activity of the Sun. According to NASA, in 2020, the Sun, which is currently in solar cycle #25, will reach its lowerst activity in over 200 years.
What is the solar cycle?
The solar cycle is a periodic 11-year fluctuation in the Sun’s magnetic field, during which its North and South poles trade places. This has an enormous effect on the number and size of sunspots, the level of solar radiation, and the ejection of solar material comprised of flares and coronal loops.
The solar cycle was first noted in 1775 by Danish astronomer Christian Horrebow who observed that the number and size of sunspots repeated itself.
In 1843, the German astronomer Samuel Heinrich Schwabe also noted this fluctuation in the number of sunspots, and Swiss astronomer Rudolf Wolf reconstructed the cycle all the way back to observations of the Sun made by Galileo.
Wolf created a sunspot counting scheme known as the Wolf Index, and a numbering scheme whereby the 1755 – 1766 cycle was designated Cycle #1.
At the beginning of a sunspot cycle, sunspots appear at the Sun’s mid-latitudes, both north and south. They then move toward the equator until a solar minimum is reached. Eventually, sunspots decay and release magnetic flux onto the Sun’s surface or photosphere.