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What Caused Napoleon’s Defeat at Waterloo?

Electrically charged volcanic ash short-circuited the Earth’s atmosphere in 1815, causing global poor weather and Napoleon’s defeat, says new research. Historians know that rainy and muddy conditions helped the Allied army defeat the French Emperor Napoleon Bonaparte at the Battle of Waterloo. The June 1815 event changed the course of European history.

Two months prior, volcano Mount Tambora erupted on the Indonesian island of Sumbawa, killing 100,000 people and plunging the Earth into a “year without a summer” in 1816. Now, Dr. Matthew Genge from Imperial College London has discovered that electrified volcanic ash from eruptions can “short-circuit” the electrical current of the ionosphere — the upper level of the atmosphere that is responsible for cloud formation.

The findings, published in Geology, could confirm the suggested link between the eruption and Napoleon’s defeat. Dr. Genge, from Imperial’s Department of Earth Science and Engineering, suggests that the Tambora eruption short-circuited the ionosphere, ultimately leading to a pulse of cloud formation. This brought heavy rain across Europe that contributed to Napoleon Bonaparte’s defeat.

The paper shows that eruptions can hurl ash much higher than previously thought into the atmosphere — up to 100 km above ground. Dr. Genge said:

Levitating volcanic ash

A series of experiments showed that that electrostatic forces could lift ash far higher than by buoyancy alone. Dr. Genge created a model to calculate how far charged volcanic ash could levitate and found that particles smaller than 0.2 millionths of a meter in diameter could reach the ionosphere during large eruptions. He said:

The experimental results are consistent with historical records from other eruptions. Weather records are sparse for 1815, so to test his theory, Dr. Genge examined weather records following the 1883 eruption of another Indonesian volcano, Krakatau. The data showed lower average temperatures and reduced rainfall almost immediately after the eruption began, and global rainfall was lower during the eruption than either period before or after.

Ionosphere disturbances and rare clouds

He also found reports of ionosphere disturbance after the 1991 eruption of Mount Pinatubo, Philippines, which could have been caused by charged ash in the ionosphere from the volcano plume. In addition, a special cloud type appeared more frequently than usual following the Krakatau eruption.

Noctilucent clouds are rare and luminous, and form in the ionosphere. Dr. Genge suggests these clouds therefore provide evidence for the electrostatic levitation of ash from large volcanic eruptions:

Provided by:  Imperial College London [Note: Materials may be edited for content and length.]

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  • Troy was born and raised in Australia and has always wanted to know why and how things work, which led him to his love for science. He is a professional photographer and enjoys taking pictures of Australia's beautiful landscapes. He is also a professional storm chaser where he currently lives in Hervey Bay, Australia.

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