IF YOU want to see Venice while keeping your feet dry, don鈥檛 go when the sun has lots of spots. Peaks in cause the city to flood more often, apparently by changing the paths of storms over Europe.
Several times a year, but most commonly between October and December, Venice is hit by an exceptional tide called the . at the University of Lisbon, Portugal, and colleagues were intrigued by studies showing the tides followed an 11-year cycle, just like the sun, showing peaks when the sunspots were most abundant. They looked at hourly observations of sea level between 1948 and 2008, which confirmed that the number of extreme tides followed peaks in the solar cycle ().
Records of air pressure over Europe over the same period revealed 鈥�acqua alta years鈥� saw a lot of low-pressure systems over the north Adriatic Sea, while in quiet years these systems were further south.
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This make sense, because flooding events in Venice are known to be triggered by low-pressure systems from the Atlantic. These systems allow sea levels to rise, while stormy winds blow from south to north, piling up seawater around Venice. In quiet solar years, the storms are shifted to the south, but it remains unclear exactly how solar activity has these effects on the weather.
