Do Sunspots Influence Weather?
Scientists have long suspected that sunspots have an effect on Earth's weather, and according to a new study, published in the journal Geophysical Research Letters, they do. Researchers found that unusually cold winters are linked to periods of low sunspot activity, and that the Rhine, Germany's largest river, is the key.
Researchers looked at when the Rhine froze, and found that since 1780, the Rhine has frozen 14 times, and of those times, 10 occurred during times of low sunspot activity.
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"The advantage with studying the Rhine is because it's a very simple measurement," Frank Sirocko, lead author of the study and professor of stedimentology and paleoclimatology at the Institute of Geosciences of Johannes Gutenberg University in Mainz, Germany, said in a statement. "Freezing is special in that it's like an on-off mode. Either there is ice or there is no ice."
Researchers said it's the first time a common link has been found between usually cold winters in Germany.
"We provide, for the first time, statistically robust evidence that the succession of cold winters during the last 230 years in Central Europe has a common cause,"Sirocko said.
The sun maintains an 11-year solar cycle of two periods: solar maximum and solar minimum, measured by the number of sunspots. Solar storms usually occur in the presence of sunspots, according to NASA.
During solar maximum, several hundred sunspots dot the sun each day, but several days may pass without any sunspots during solar minimum. The sun entered solar minimum in 2007.
Sunspots are also precursors to solar flares and solar storms, which can cause blackouts and disrupt GPS signals.
When sunspots are down, the sun emits less radiation, which causes a change in the circulation patterns of the two lowest atmospheric levels. This change influences wind patterns and causes unusually cold winters.
"Due to this indirect effect, the solar cycle does not impact hemispherically averaged temperatures, but only leads to regional temperature anomalies," Stephan Pfahl, study coauthor and researcher at the Institute for Atmospheric and Climate Science in Zurich, said in a statement.
Thomas Crowley, director of the Scottish Alliance for Geoscience, Environment, and Society, who was not involved with the study, said that the link between sunspots and weather is strong.
"There is some suspension of belief in this link," he said in a statement. "This study tilts the argument more towards thinking there really is something to this link. If you have more statistical evidence to support this explanation, one is more likely to say it's true."
Solar storms increase the electric current of the ionosphere, a part of Earth's atmosphere. Many communications systems, such as AM radio, transmit signals over long distances using the ionosphere as a reflector. Increases in electric current can disrupt that reflection. Airlines rely on radio to communicate with ground control, and solar storms can disrupt that communication.
Flares also cause a change in the density of the ionosphere and cause GPS systems to become less precise, experts said. Magnetic fields that accompany solar storms can short electrical grids and knock out power.
Solar storms also cause more innocuous auroras, a collection of green, red and blue lights strongest around the poles. Strong solar storms can create auroras as far south as the Great Lakes.
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