Volcanic lightning

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Volcanic lightning
Taal Lightning Strike During Eruption.jpg
Volcanic lightning during the January 2020 eruption of Taal Volcano
EffectLightning

Volcanic lightning is an electrical discharge caused by a volcanic eruption rather than from an ordinary thunderstorm. Volcanic lightning arises from colliding, fragmenting particles of volcanic ash (and sometimes ice), [1] [2] which generate static electricity within the volcanic plume, [3] leading to the name dirty thunderstorm. [4] [5] Moist convection currents and ice formation also drive the eruption plume dynamics [6] [7] and can trigger volcanic lightning. [8] [9] Unlike ordinary thunderstorms, volcanic lightning can also occur when there are no ice crystals in the ash cloud. [10] [11]

Contents

The earliest recorded observations of volcanic lightning [12] are from Pliny the Younger, describing the eruption of Mount Vesuvius in 79 AD, "There was a most intense darkness rendered more appalling by the fitful gleam of torches at intervals obscured by the transient blaze of lightning." [13] The first studies of volcanic lightning were also conducted at Mount Vesuvius by Luigi Palmieri [14] who observed the eruptions of 1858, 1861, 1868, and 1872 from the Vesuvius Observatory. These eruptions often included lightning activity. [13]

Instances have been reported above Alaska's Mount Augustine volcano, [15] Iceland's Eyjafjallajökull and Grimsvotn, [16] Mount Etna in Sicily, Italy, [17] Taal Volcano in the Philippines [18] [19] and Mount Ruang in Indonesia. [20]

Charging mechanisms

Ice charging

1994 eruption of Mount Rinjani Rinjani 1994.jpg
1994 eruption of Mount Rinjani

Ice charging is thought to play an important role in certain types of eruption plumes – particularly those rising above the freezing level or involving magma-water interaction. [21] Ordinary thunderstorms produce lightning through ice charging [22] as water clouds become electrified from colliding ice crystals and other hydrometeors. [23] Volcanic plumes can also carry abundant water. [24] This water is sourced from the magma, [25] vaporized from surrounding sources such as lakes and glaciers, [26] and entrained from ambient air as the plume rises through the atmosphere. [6] One study suggested that the water content of volcanic plumes can be greater than that of thunderstorms. [27] The water is initially transported as a hot vapor, which condenses to liquid in the rising column and ultimately freezes to ice if the plume cools well below freezing. [28] Some eruptions even produce volcanic hail. [7] [29] Support for the ice-charging hypothesis includes the observation that lightning activity greatly increases once volcanic plumes rise above the freezing level, [30] [21] and evidence that ice crystals in the anvil top of the volcanic cloud are effective charge-carriers. [9]

Frictional charging

Triboelectric (frictional) charging within the plume of a volcano during eruption is thought to be a major electrical charging mechanism. Electrical charges are generated when rock fragments, ash, and ice particles in a volcanic plume collide and produce static charges, similar to the way that ice particles collide in regular thunderstorms. [12] The convective activity causing the plume to rise then separates the different charge regions, ultimately causing electrical breakdown.

Fractoemission

Fractoemission is the generation of charge through break-up of rock particles. It may be a significant source of charge near the erupting vent. [31]

Radioactive charging

Although it is thought to have a small effect on the overall charging of volcanic plumes, naturally occurring radioisotopes within ejected rock particles may nevertheless influence particle charging. [32] In a study performed on ash particles from the Eyjafjallajökull and Grímsvötn eruptions, scientists found that both samples possessed a natural radioactivity above the background level, but that radioisotopes were an unlikely source of self-charging in the Eyjafjallajökull plume. [33] However, there was the potential for greater charging near the vent where the particle size is larger. [32] Research continues, and the electrification via radioisotopes, such as radon, may in some instances be significant and at various magnitudes a somewhat common mechanism. [34]

Plume height

The height of the ash plume appears to be linked with the mechanism which generates the lightning. In taller ash plumes (7–12 km) large concentrations of water vapor may contribute to lightning activity, while smaller ash plumes (1–4 km) appear to gain more of their electric charge from fragmentation of rocks near the vent of the volcano (fractoemission). [30] The atmospheric temperature also plays a role in the formation of lightning. Colder ambient temperatures promote freezing and ice charging inside the plume, thus leading to more electrical activity. [35] [33]

Lightning-induced volcanic spherules

Experimental studies and investigation of volcanic deposits have shown that volcanic lighting creates a by-product known as "lightning-induced volcanic spherules" (LIVS). [36] [37] These tiny glass spherules form during high-temperatures processes such as cloud-to-ground lightning strikes, analogous to fulgurites. [36] The temperature of a bolt of lightning can reach 30,000 °C. When this bolt contacts ash particles within the plume it may do one of two things: (1) completely vaporize the ash particles, [38] or (2) cause them to melt and then quickly solidify as they cool, forming orb shapes. [37] The presence of lightning-induced volcanic spherules may provide geological evidence for volcanic lightning when the lightning itself was not observed directly. [36]

Related Research Articles

<span class="mw-page-title-main">Lightning</span> Weather phenomenon involving electrostatic discharge

Lightning is a natural phenomenon formed by electrostatic discharges through the atmosphere between two electrically charged regions, either both in the atmosphere or one in the atmosphere and one on the ground, temporarily neutralizing these in a near-instantaneous release of an average of between 200 megajoules and 7 gigajoules of energy, depending on the type. This discharge may produce a wide range of electromagnetic radiation, from heat created by the rapid movement of electrons, to brilliant flashes of visible light in the form of black-body radiation. Lightning causes thunder, a sound from the shock wave which develops as gases in the vicinity of the discharge experience a sudden increase in pressure. Lightning occurs commonly during thunderstorms as well as other types of energetic weather systems, but volcanic lightning can also occur during volcanic eruptions. Lightning is an atmospheric electrical phenomenon and contributes to the global atmospheric electrical circuit.

<span class="mw-page-title-main">Volcanism of Iceland</span>

Iceland experiences frequent volcanic activity, due to its location both on the Mid-Atlantic Ridge, a divergent tectonic plate boundary, and being over a hot spot. Nearly thirty volcanoes are known to have erupted in the Holocene epoch; these include Eldgjá, source of the largest lava eruption in human history. Some of the various eruptions of lava, gas and ash have been both destructive of property and deadly to life over the years, as well as disruptive to local and European air travel.

<span class="mw-page-title-main">Eyjafjallajökull</span> Glacier and volcano in Iceland

Eyjafjallajökull, sometimes referred to by the numeronym E15, is one of the smaller ice caps of Iceland, north of Skógar and west of Mýrdalsjökull. The ice cap covers the caldera of a volcano with a summit elevation of 1,651 metres (5,417 ft). The volcano has erupted relatively frequently since the Last Glacial Period, most recently in 2010, when, although relatively small for a volcanic eruption, it caused enormous disruption to air travel across northern and western Europe for a week.

<span class="mw-page-title-main">Grímsvötn</span> Volcano in Iceland

Grímsvötn is an active volcano with a fissure system located in Vatnajökull National Park, Iceland. The volcano itself is completely subglacial and located under the northwestern side of the Vatnajökull ice cap. The subglacial caldera is at 64°25′N17°20′W, at an elevation of 1,725 m (5,659 ft). Beneath the caldera is the magma chamber of the Grímsvötn volcano.

<span class="mw-page-title-main">Plinian eruption</span> Type of volcanic eruption

Plinian eruptions or Vesuvian eruptions are volcanic eruptions marked by their similarity to the eruption of Mount Vesuvius in 79 AD, which destroyed the ancient Roman cities of Herculaneum and Pompeii. The eruption was described in a letter written by Pliny the Younger, after the death of his uncle Pliny the Elder.

<span class="mw-page-title-main">Strombolian eruption</span> Type of volcanic eruption with relatively mild explosive intensity

In volcanology, a Strombolian eruption is a type of volcanic eruption with relatively mild blasts, typically having a Volcanic Explosivity Index of 1 or 2. Strombolian eruptions consist of ejection of incandescent cinders, lapilli, and volcanic bombs, to altitudes of tens to a few hundreds of metres. The eruptions are small to medium in volume, with sporadic violence. This type of eruption is named for the Italian volcano Stromboli.

<span class="mw-page-title-main">Volcanic gas</span> Gases given off by active volcanoes

Volcanic gases are gases given off by active volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic craters or vents. Volcanic gases can also be emitted through groundwater heated by volcanic action.

<span class="mw-page-title-main">Geology of Iceland</span>

The geology of Iceland is unique and of particular interest to geologists. Iceland lies on the divergent boundary between the Eurasian plate and the North American plate. It also lies above a hotspot, the Iceland plume. The plume is believed to have caused the formation of Iceland itself, the island first appearing over the ocean surface about 16 to 18 million years ago. The result is an island characterized by repeated volcanism and geothermal phenomena such as geysers.

<span class="mw-page-title-main">Cumulonimbus flammagenitus</span> Thunderstorm cloud that forms above a heat source

The cumulonimbus flammagenitus cloud (CbFg), also known as the pyrocumulonimbus cloud, is a type of cumulonimbus cloud that forms above a source of heat, such as a wildfire or volcanic eruption, and may sometimes even extinguish the fire that formed it. It is the most extreme manifestation of a flammagenitus cloud. According to the American Meteorological Society’s Glossary of Meteorology, a flammagenitus is "a cumulus cloud formed by a rising thermal from a fire, or enhanced by buoyant plume emissions from an industrial combustion process."

<span class="mw-page-title-main">Types of volcanic eruptions</span> Overview of different types of volcanic eruptions

Several types of volcanic eruptions—during which material is expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.

<span class="mw-page-title-main">Phreatomagmatic eruption</span> Volcanic eruption involving both steam and magma

Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions contain juvenile (magmatic) clasts. It is common for a large explosive eruption to have magmatic and phreatomagmatic components.

<span class="mw-page-title-main">Volcanism on Venus</span> Overview of volcanic activity on the planet Venus

The surface of Venus is dominated by volcanic features and has more volcanoes than any other planet in the Solar System. It has a surface that is 90% basalt, and about 65% of the planet consists of a mosaic of volcanic lava plains, indicating that volcanism played a major role in shaping its surface. There are more than 1,000 volcanic structures and possible periodic resurfacing of Venus by floods of lava. The planet may have had a major global resurfacing event about 500 million years ago, from what scientists can tell from the density of impact craters on the surface. Venus has an atmosphere rich in carbon dioxide, with a pressure that is 90 times that of Earth's atmosphere.

<span class="mw-page-title-main">2010 eruptions of Eyjafjallajökull</span> Volcanic events in Iceland

Between March and June 2010 a series of volcanic events at Eyjafjallajökull in Iceland caused enormous disruption to air travel across Western Europe.

<span class="mw-page-title-main">Gas slug</span> Conglomerate of high pressure gas bubbles

A gas slug is a conglomerate of high pressure gas bubbles that forms within certain volcanoes, the agitation of which is a driving factor in Strombolian eruptions. They start out as small bubbles of gas inside of volcanic magma. These accumulate into one large bubble, which starts to rise through the lava plume. Gas slugs also consist of many chemical properties that assist scientists in monitoring volcanic eruptions.

<span class="mw-page-title-main">1808 mystery eruption</span> Volcanic eruption in southwest Pacific

The 1808 mystery eruption is one or potentially multiple unidentified volcanic eruptions that resulted in a significant rise in stratospheric sulfur aerosols, leading to a period of global cooling analogous to the Year Without a Summer in 1816.

<span class="mw-page-title-main">Volcanic ash</span> Natural material created during volcanic eruptions

Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products, including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away.

<span class="mw-page-title-main">Campanian Ignimbrite eruption</span> Volcanic eruption about 40,000 years ago

The Campanian Ignimbrite eruption was a major volcanic eruption in the Mediterranean during the late Quaternary, classified 7 on the Volcanic Explosivity Index (VEI). The event has been attributed to the Archiflegreo volcano, the 12-by-15-kilometre-wide caldera of the Phlegraean Fields, located 20 km (12 mi) west of Mount Vesuvius under the western outskirts of the city of Naples and the Gulf of Pozzuoli, Italy. Estimates of the date and magnitude of the eruption(s), and the amount of ejected material have varied considerably during several centuries the site has been studied. This applies to most significant volcanic events that originated in the Campanian Plain, as it is one of the most complex volcanic structures in the world. However, continued research, advancing methods, and accumulation of volcanological, geochronological, and geochemical data have improved the dates' accuracy.

<span class="mw-page-title-main">Tamsin Mather</span> Professor of Earth Sciences

Tamsin Alice Mather is a British Professor of Earth Sciences at the Department of Earth Sciences, University of Oxford and a Fellow of University College, Oxford. She studies volcanic processes and their impacts on the Earth's environment and has appeared on the television and radio.

Karen Aplin is a British atmospheric and space physicist. She is currently a professor at the University of Bristol. Aplin has made significant contributions to interdisciplinary aspects of space and terrestrial science, in particular the importance of electrical effects on planetary atmospheres. She was awarded the 2021 James Dungey Lectureship of the Royal Astronomical Society.

The 1452/1453 mystery eruption is an unidentified volcanic event that triggered the first large sulfate spike in the 1450s, succeeded by another spike in 1458 caused by another mysterious eruption. The eruption caused a severe volcanic winter leading to one of strongest cooling events in the Northern Hemisphere. This date also coincides with a substantial intensification of the Little Ice Age.

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