https://education.nationalgeographic.org/resource/human-environmental-impact-volcanic-ash/
Volcanic Ash Impacts
Plumes of volcanic ash can spread over large areas of sky, turning daylight into complete darkness and drastically reducing visibility. These enormous and menacing clouds are often accompanied by thunder and lightning. Volcanic lightning is a unique phenomenon and scientists continue to debate the way it works. Many scientists think that the sheer energy of a volcanic explosion charges its ash particles with electricity. Positively charged particles meet up with negatively charged particles, either in the cooler atmosphere or in the volcanic debris itself. Lightning bolts then occur as a means of balancing these charge distributions.
Volcanic ash and gases can sometimes reach the stratosphere, the upper layer in Earth’s atmosphere. This volcanic debris can reflect incoming solar radiation and absorb outgoing land radiation, leading to a cooling of the Earth’s temperature. In extreme cases, these “volcanic winters” can affect weather patterns across the globe. The 1815 eruption of Mount Tambora, Indonesia, the largest eruption in recorded history, ejected an estimated 150 cubic kilometers (36 cubic miles) of debris into the air. The average global temperature cooled by as much as 3° Celsius (5.4° Fahrenheit), causing extreme weather around the world for a period of three years. As a result of Mount Tambora’s volcanic ash, North America and Europe experienced the “Year Without a Summer” in 1816. This year was characterized by widespread crop failure, deadly famine, and disease.
Airborne volcanic ash is especially dangerous to moving aircraft. The small, abrasive particles of rock and glass can melt inside an airplane engine and solidify on the turbine blades—causing the engine to stall. Air traffic controllers take special precautions when volcanic ash is present. The 2010 eruption of Eyjafjallajökull, Iceland, produced an ash cloud that forced the cancelation of roughly 100,000 flights and affected seven million passengers, costing the aviation industry an estimated $2.6 billion.
Volcanic ash can impact the infrastructure of entire communities and regions. Ash can enter and disrupt the functioning of machinery found in power supply, water supply, sewage treatment, and communication facilities. Heavy ash fall can also inhibit road and rail traffic and damage vehicles. When mixed with rainfall, volcanic ash turns into a heavy, cement-like sludge that is able to collapse roofs. In 1991, Mount Pinatubo erupted in the Philippines at the same time that a massive tropical storm wreaked havoc in the area. Heavy rains mixed with the ash fall, collapsing the roofs of houses, schools, businesses, and hospitals in three different provinces.
Ash also poses a threat to ecosystems, including people and animals. Carbon dioxide and fluorine, gases that can be toxic to humans, can collect in volcanic ash. The resulting ash fall can lead to crop failure, animal death and deformity, and human illness. Ash’s abrasive particles can scratch the surface of the skin and eyes, causing discomfort and inflammation. If inhaled, volcanic ash can cause breathing problems and damage the lungs. Inhaling large amounts of ash and volcanic gases can cause a person to suffocate. Suffocation is the most common cause of death from a volcano.
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