If we talk about the climate, then 1816 was, frankly, strange. The months, usually warm and pleasant, were cold, rainy and overcast, resulting in crop shortages across much of the Northern Hemisphere. It was associated with one of the most powerful volcanic eruptions in history. A new study from Imperial College London explains how electrified volcanic ash could short-circuit Earth's ionosphere and trigger a Year Without Summer.
In April 1815, the volcanic activity of Tambor (volcano, Indonesia) peaked, and after several months of rumbling and rumbling, an eruption occurred, which reached 7 on the volcanic activity scale (VEI). It was the largest volcanic eruption since 180 BC, when the explosion was heard at a distance of 2600 km.
Most importantly, the volcano has released about 10 billion tons of ash into the atmosphere.
As a result of the eruption of 1815, a developed culture was buried under a three-meter layer of pyroclastic deposits at the foot of the great volcano. Over the next year, this dense ash cloud covered the Earth, reflecting sunlight and dropping temperatures significantly. Nearly 100,000 people are believed to have died as a result of food shortages.
Although the connection between the eruption and the "Year without Summer" has long been proven, exactly which mechanisms played a key role "in the game" remained a mystery. A study by Imperial College London aims to explain how this dramatic event played out.
“Previously, geologists believed that volcanic ash would get stuck in the lower atmosphere,” says Matthew Genge, lead author of the study. "My studies, however, show that it can be thrown into the upper layers by electrical impulses."
As impressive pictures of lightning passing through volcanic plumes show, the ash is electrically charged. According to Genge, the interaction of electrostatic forces could lift these ash even higher than previously thought.
"Volcanic plumes can carry negative electrical charges, and thus, the plume pushes the ash, lifting it high into the atmospheric layers," says Jenge. "The effect is very similar to the repulsion of two magnets when their poles coincide."
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To test his idea, Jenj ran an experiment to find out how much charged volcanic ash would rise under these conditions. His experiments showed that especially strong eruptions can launch particles up to 500 nanometers into the ionosphere.
This is important because the ionosphere is an electrically active region of the earth's atmosphere. According to Jenj, charged particles can “short out” the ionosphere, causing climate anomalies such as increased cloud cover that reflects sunlight and cools the planet's surface.
Interestingly, all the stars came together to make 1816 a colder year. The eruption occurred at the end of the global cooling, also known as the Little Ice Age, spanning the years from the 16th to the mid-19th centuries. It also fell in the middle of the Dalton Low, when the Sun's activity was the lowest ever recorded in history. So the eruption of Mount Tambora seems to have been just the finishing touch to the picture of Mother Earth.
To test the theory, Jenge examined weather data following the massive eruption of Mount Krakatoa decades later, in 1883. The data collected by the researchers showed that the average air temperature and rainfall dropped almost immediately after the eruption began.
Genj also noted that noctilucent clouds, usually glowing at night, which form in the ionosphere, appeared more often after the eruption of Krakatoa. The recent eruption of Mount Pinatubo in 1991 also resulted in ionospheric disturbances.