Why meteorologists hold their breath when a volcano erupts in the tropics
By
Adriana Navarro, AccuWeather staff writer
Published Aug. 12, 2020 9:41 AM
The village of Karo, Indonesia, was coated in ash on Aug. 10, after a volcanic eruption at Mount Sinabung.
Ash and debris choked the air around Indonesia's Mt. Sinabung on Monday, two days after an earlier eruption stirred it from its inactivity.
Dramatic footage showed a plume of ash and debris that had been jettisoned to a height of up to 16,400 feet (5,000 meters) into the sky. The monstrous cloud hung in the sky as the volcano growled and rumbled.
"The sound was like thunder, it lasted for less than 30 seconds," resident Fachrur Rozi Pasi told Reuters.
Daylight dimmed in Berastragi, about 12.4 miles from the crater, and The Associated Press noted motorists switched on their headlights to see through the ash.
A thick layer of ash coated, crops, cars and buildings in Karo, the regency in North Sumatra, Indonesia, where Mt. Sinabung is located. Up to 2 inches (5 centimeters) of falling grit and ash had accumulated in already abandoned villages near the volcano, Armen Putra, an official at the Sinabung monitoring post on Sumatra Island, told The Associated Press.
Mount Sinabung spews volcanic materials into the air as it erupts, in Karo, North Sumatra, Indonesia, Monday, Aug. 10, 2020. The rumbling volcano erupted Monday, sending a column of volcanic materials a few thousands meters into the sky. Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific basin. (AP Photo/Sugeng Nuryono)
Although overall rainfall looks near to a bit below average over the next week for the area, AccuWeather Senior Meteorologist David Samuhel warned that with newly fallen ash, locally very heavy rain could cause a lahar, a type of mudflow that can occur after a volcanic eruption or simply near a volcano after heavy rainfall.
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Sinabung is one of the more than 120 active volcanoes in Indonesia, having previously been dormant until it erupted in 2010, ending 400 years of dormancy. Since then, it has erupted multiple times, killing at least 16 people in an eruption on Feb. 1, 2014, according to the AP. Another seven people died in a 2016 eruption.
The volcano is located on the Pacific "Ring of Fire," an archway of volcanoes situated along fault lines around the Pacific.
Indonesia's Volcanology and Geological Hazard Mitigation reported there were no fatalities or injuries from the eruption, and also advised villagers to stay about 3 miles from the crater's mouth and to be aware of the danger of lava. Air travel has not been impacted by the ash so far, the Transport Ministry said.
However, the ash poses more than just visibility problems.
A car drives on a road covered with volcanic ash from the eruption of Mount Sinabung, in Karo, North Sumatra, Indonesia, Monday, Aug. 10, 2020. The rumbling volcano erupted Monday, sending a column of volcanic materials a few thousands meters into the sky. Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific basin. (AP Photo/Sugeng Nuryono)
"The ash certainly poses a health threat to those near the volcano," Samuhel said. "It can also collect on roofs and cause them to fail."
"The situation around Mt. Sinabung is very dark now," Gilbert Sembiring, who had been visiting a friend in Naman Teran Kampung when the volcano erupted, told Reuters. "It was bigger than the eruption a couple of days ago."
Sinabung had had a smaller eruption on Saturday, Aug. 8, according to the local news agency The Jakarta Post.
Volcano eruptions have had a history of not just blotting out the sky, but even impacting global temperatures.
"When volcanic ashes and gasses reach the stratosphere, they get trapped there and can fan out over a large area, blocking sunlight, resulting in cooling across the globe," Samuhel said.
This happens, AccuWeather Senior Meteorologist and Long-Range Forecaster Paul Pastelok explains, through a large enough eruption pushing sulfur dioxide and ash to the upper troposphere and into the stratosphere, which is at an elevation of about 30,000 feet, or a bit over 5 miles.
The Sinabung eruption on Aug. 10 reached a little over half of that height at 16,400 feet -- over 3 miles.
Indonesian men use their mobile phones to take photos as Mount Sinabung spews volcanic materials into the air as it erupts, in Karo, North Sumatra, Indonesia, Monday, Aug. 10, 2020. The rumbling volcano erupted Monday, sending a column of volcanic materials a few thousands meters into the sky. Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific basin. (AP Photo/Sugeng Nuryono)
"Volcanoes do affect the weather, and some major ones affect the climate if you define climate as anything beyond a year or two," Dr. Joel Myers, Founder CEO and Chairman of AccuWeather, said.
A clear example of this occurred a little over 200 years ago when the Tambora volcano, also located in what is now Indonesia, erupted in April 1815, killing more than 600,000 people.
The eruption "caused a few years of cold weather, some of it extraordinary," Myers explained. "This includes 1816, the 'Year Without a Summer,' when frost occurred in New England in every month of the year -- affecting crops and on one July day when snow flurries were reported in Long Island Sound."
The location of the volcanic eruption will also determine how likely it is to impact global temperatures.
"When volcanoes erupt in the tropical regions, they have a better chance to impact global temperatures than northern eruptions," Pastelok said.
This is because most of the sulfur dioxide and ash spewed from eruptions north are more likely to get caught up in the northern polar jet stream, possibly being dispersed out quickly over the northern latitudes. Likewise, the southern polar jet stream acts the same below the tropics.
"They both do the same thing, pushing ash and sulfur, leading to blocking particle formation in the upper atmosphere, which prohibits too much radiant energy to reach the lower atmosphere, thus less warming overall."
An eruption in the tropics however, can loom "over a greater area and take a longer duration for the aerosols to disperse over time with a slower jet stream pattern over the tropics," Pastelok said.
Once the aerosols infiltrate the stratosphere and begin to linger, they begin to block energy from the sun, gradually warming the stratosphere. As this happens, Pastelok explained, the area over and near the tropics cools more.
"In the winter, this weakens the temperature difference between the tropical region and the far northern latitudes," Pastelok said. "This can impact certain tele-connections like the Arctic Oscillation (AO), which, when strong, keeps colder air bottled up near the poles, but when weakened can allow colder air to spill toward the middle latitudes."
The pocket of cold air that sits over the poles, occasionally escaping through the AO is referred to as the polar vortex.
The AO fluctuates throughout the winter, but a stronger temperature difference would lead to a frequently weaker AO, meaning colder air reaching the U.S. more frequently.
A weaker temperature difference, which sulfur dioxide and ash expelled into the stratosphere in the tropics can lead to, would more frequently lead to a stronger AO, Pastelok explained. A stronger AO means certain areas like the eastern U.S. remain warmer than normal during the wintertime.
"Global temperatures can be impacted by 1 to 2 degrees C over a two-to-three-year period during a major eruption," Pastelok said.
The last significant volcanic eruption to throw global temperatures was the eruption of Mount Pinatubo in the Philippines in 1991. The eruption spewed ash and debris up to 131,234 feet, over 24 miles, into the air and unleashed about 17 megatons of sulfur dioxide into the atmosphere.
As a result, Dr. Howard Diamond, manager of the Climate Science Program at NOAA's Air Resources Laboratory told AccuWeather, there was an observed surface cooling in the Northern Hemisphere of up to 0.5 to 0.6 degrees Celsius, and a cooling of perhaps as large as minus 0.4 degrees Celsius across parts of the world from 1992 to 1993.
Additional reporting by Chaffin Mitchell and Brian Lada.
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
Report a Typo
News / Weather News
Why meteorologists hold their breath when a volcano erupts in the tropics
By Adriana Navarro, AccuWeather staff writer
Published Aug. 12, 2020 9:41 AM
The village of Karo, Indonesia, was coated in ash on Aug. 10, after a volcanic eruption at Mount Sinabung.
Ash and debris choked the air around Indonesia's Mt. Sinabung on Monday, two days after an earlier eruption stirred it from its inactivity.
Dramatic footage showed a plume of ash and debris that had been jettisoned to a height of up to 16,400 feet (5,000 meters) into the sky. The monstrous cloud hung in the sky as the volcano growled and rumbled.
"The sound was like thunder, it lasted for less than 30 seconds," resident Fachrur Rozi Pasi told Reuters.
Daylight dimmed in Berastragi, about 12.4 miles from the crater, and The Associated Press noted motorists switched on their headlights to see through the ash.
A thick layer of ash coated, crops, cars and buildings in Karo, the regency in North Sumatra, Indonesia, where Mt. Sinabung is located. Up to 2 inches (5 centimeters) of falling grit and ash had accumulated in already abandoned villages near the volcano, Armen Putra, an official at the Sinabung monitoring post on Sumatra Island, told The Associated Press.
Mount Sinabung spews volcanic materials into the air as it erupts, in Karo, North Sumatra, Indonesia, Monday, Aug. 10, 2020. The rumbling volcano erupted Monday, sending a column of volcanic materials a few thousands meters into the sky. Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific basin. (AP Photo/Sugeng Nuryono)
Although overall rainfall looks near to a bit below average over the next week for the area, AccuWeather Senior Meteorologist David Samuhel warned that with newly fallen ash, locally very heavy rain could cause a lahar, a type of mudflow that can occur after a volcanic eruption or simply near a volcano after heavy rainfall.
CLICK HERE FOR THE FREE ACCUWEATHER APP
Sinabung is one of the more than 120 active volcanoes in Indonesia, having previously been dormant until it erupted in 2010, ending 400 years of dormancy. Since then, it has erupted multiple times, killing at least 16 people in an eruption on Feb. 1, 2014, according to the AP. Another seven people died in a 2016 eruption.
The volcano is located on the Pacific "Ring of Fire," an archway of volcanoes situated along fault lines around the Pacific.
Indonesia's Volcanology and Geological Hazard Mitigation reported there were no fatalities or injuries from the eruption, and also advised villagers to stay about 3 miles from the crater's mouth and to be aware of the danger of lava. Air travel has not been impacted by the ash so far, the Transport Ministry said.
However, the ash poses more than just visibility problems.
A car drives on a road covered with volcanic ash from the eruption of Mount Sinabung, in Karo, North Sumatra, Indonesia, Monday, Aug. 10, 2020. The rumbling volcano erupted Monday, sending a column of volcanic materials a few thousands meters into the sky. Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific basin. (AP Photo/Sugeng Nuryono)
"The ash certainly poses a health threat to those near the volcano," Samuhel said. "It can also collect on roofs and cause them to fail."
"The situation around Mt. Sinabung is very dark now," Gilbert Sembiring, who had been visiting a friend in Naman Teran Kampung when the volcano erupted, told Reuters. "It was bigger than the eruption a couple of days ago."
Sinabung had had a smaller eruption on Saturday, Aug. 8, according to the local news agency The Jakarta Post.
Volcano eruptions have had a history of not just blotting out the sky, but even impacting global temperatures.
"When volcanic ashes and gasses reach the stratosphere, they get trapped there and can fan out over a large area, blocking sunlight, resulting in cooling across the globe," Samuhel said.
This happens, AccuWeather Senior Meteorologist and Long-Range Forecaster Paul Pastelok explains, through a large enough eruption pushing sulfur dioxide and ash to the upper troposphere and into the stratosphere, which is at an elevation of about 30,000 feet, or a bit over 5 miles.
The Sinabung eruption on Aug. 10 reached a little over half of that height at 16,400 feet -- over 3 miles.
Indonesian men use their mobile phones to take photos as Mount Sinabung spews volcanic materials into the air as it erupts, in Karo, North Sumatra, Indonesia, Monday, Aug. 10, 2020. The rumbling volcano erupted Monday, sending a column of volcanic materials a few thousands meters into the sky. Sinabung is among more than 120 active volcanoes in Indonesia, which is prone to seismic upheaval due to its location on the Pacific "Ring of Fire," an arc of volcanoes and fault lines encircling the Pacific basin. (AP Photo/Sugeng Nuryono)
"Volcanoes do affect the weather, and some major ones affect the climate if you define climate as anything beyond a year or two," Dr. Joel Myers, Founder CEO and Chairman of AccuWeather, said.
A clear example of this occurred a little over 200 years ago when the Tambora volcano, also located in what is now Indonesia, erupted in April 1815, killing more than 600,000 people.
The eruption "caused a few years of cold weather, some of it extraordinary," Myers explained. "This includes 1816, the 'Year Without a Summer,' when frost occurred in New England in every month of the year -- affecting crops and on one July day when snow flurries were reported in Long Island Sound."
The location of the volcanic eruption will also determine how likely it is to impact global temperatures.
"When volcanoes erupt in the tropical regions, they have a better chance to impact global temperatures than northern eruptions," Pastelok said.
This is because most of the sulfur dioxide and ash spewed from eruptions north are more likely to get caught up in the northern polar jet stream, possibly being dispersed out quickly over the northern latitudes. Likewise, the southern polar jet stream acts the same below the tropics.
"They both do the same thing, pushing ash and sulfur, leading to blocking particle formation in the upper atmosphere, which prohibits too much radiant energy to reach the lower atmosphere, thus less warming overall."
An eruption in the tropics however, can loom "over a greater area and take a longer duration for the aerosols to disperse over time with a slower jet stream pattern over the tropics," Pastelok said.
Once the aerosols infiltrate the stratosphere and begin to linger, they begin to block energy from the sun, gradually warming the stratosphere. As this happens, Pastelok explained, the area over and near the tropics cools more.
"In the winter, this weakens the temperature difference between the tropical region and the far northern latitudes," Pastelok said. "This can impact certain tele-connections like the Arctic Oscillation (AO), which, when strong, keeps colder air bottled up near the poles, but when weakened can allow colder air to spill toward the middle latitudes."
The pocket of cold air that sits over the poles, occasionally escaping through the AO is referred to as the polar vortex.
The AO fluctuates throughout the winter, but a stronger temperature difference would lead to a frequently weaker AO, meaning colder air reaching the U.S. more frequently.
A weaker temperature difference, which sulfur dioxide and ash expelled into the stratosphere in the tropics can lead to, would more frequently lead to a stronger AO, Pastelok explained. A stronger AO means certain areas like the eastern U.S. remain warmer than normal during the wintertime.
"Global temperatures can be impacted by 1 to 2 degrees C over a two-to-three-year period during a major eruption," Pastelok said.
The last significant volcanic eruption to throw global temperatures was the eruption of Mount Pinatubo in the Philippines in 1991. The eruption spewed ash and debris up to 131,234 feet, over 24 miles, into the air and unleashed about 17 megatons of sulfur dioxide into the atmosphere.
As a result, Dr. Howard Diamond, manager of the Climate Science Program at NOAA's Air Resources Laboratory told AccuWeather, there was an observed surface cooling in the Northern Hemisphere of up to 0.5 to 0.6 degrees Celsius, and a cooling of perhaps as large as minus 0.4 degrees Celsius across parts of the world from 1992 to 1993.
Related:
Additional reporting by Chaffin Mitchell and Brian Lada.
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
Report a Typo