Summer’s Sphere Report
Atmosphere & Mt. Pinatubo
1. Aircraft Encounters with Ash
E>A>B
The intense eruptions of Mt. Pinatubo on June 11th, 1991 caused many disastrous effects to
aircrafts and their flight paths. The volcano injected tremendously large amounts of ash upwards
of 10,000 feet into the atmosphere. The June 15th eruption produced the largest ash cloud; it
was carried by the upper levels winds to the west and circled the globe in twenty two days.
According to the United States Geologic Service, “the June 15 cloud spread laterally to cover a
broad equatorial band from about 10 degrees south to 20 degrees north latitude and
contaminated some of the world's busiest air traffic corridors.” Between June 12th and 18th, there
were sixteen in-flight encounters with ash that spewed from the volcano. There were reportedly
more than two dozen airplanes on the ground in surrounding areas that were also physical
damaged by the volcanic ash.
References:
Casadevalla, T.J., Delos Reyes, P.J., & Schneider, D. J. The 1991 Pinatubo Eruptions and
Their Effects on Aircraft Operations. Retrieved from:
http://pubs.usgs.gov/pinatubo/casa/index.html
http://vulcan.wr.usgs.gov/Volcanoes/Philippines/Pinatubo/Publications/FireMud/CasadevallOthe
rs/framework.html
2. Greenhouse Gasses and the Haze Effect
E>A
Volcanic eruptions like the June 15th, 1991 eruption of Mt. Pinatubo can enhance global
warming by adding carbon dioxide into the atmosphere although a far greater amount of carbon
dioxide is released into the atmosphere by human activities. The small amount of global
warming caused by greenhouse gases sent out during a volcanic eruption is often offset by the
haze effect. Haze is particles of dust, volcanic ash or salt that are roughly 0.1 microns large that
are suspended in the atmosphere. The haze effect happens when particles like ash and dust
are suspended in the atmosphere and block out the sun light trying to reach Earth. Because
there is less solar radiation reaching Earth’s surface, the global temperature drops. The effect
often gives way to amazingly red sunsets that is due to particles in the stratosphere and upper
troposphere scattering the color red in the light spectrum.
References:
http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html
http://www.britannica.com/EBchecked/topic/257938/haze
http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html
3. Global Climate Change and Arctic Oscillation
E>A>H>B
Global temperature can drop by several degrees Fahrenheit when sulfur
dioxide emitted from the eruption combines with water vapor in the
stratosphere. According to Rosenberg, Mt. Pinatubo ejected somewhere
between 25 and 30 million tons of sulfur dioxide into the atmosphere and
stratosphere more specifically. In the stratosphere they form minute
sulfuric acid droplets that can lower temperatures in the troposphere
because the actually can absorb the radiation coming from the sun and
scatter it back into space. According to NASA, the 1991 eruption of the
Mount Pinatubo contributed to a strengthening of a climate pattern called
the Arctic Oscillation; this is a natural pattern of circulation of air where
the atmospheric pressure at the middle and polar latitudes change. It
thus brings lower than normal pressure to areas of the world with roughly
a forty-five degree north latitude and a higher than normal pressure at the
Polar Regions. For two years following the volcanic eruption of Mt.
Pinatubo in 1991, the entire planet cooled 0.4 to 0.8C. The largest
cooling in North America came in the summer of 1992. The ice on the
Hudson Bay melted a month later than normal, thus allowing time for the
polar bears to feed and nurse their cubs. These polar bears were called
the “Pinatubo Bears” and were a lot heavier and healthier than the polar
bears born in years before and after.
References:
Biello, D. (January 2008). Scientific Nature: Researchers Use Volcanic Eruption as Climate Lab.
Scientific America. Retrieved from: http://www.scientificamerican.com/article.cfm?id=scientificnature-researc
Holasek, R.E., King, A.J., Self, S., Torres, R.C., & Zhao, J. The Atmospheric Impact of the 1991
Mount Pinatubo Eruption. Retrieved from: http://pubs.usgs.gov/pinatubo/self/index.html
Myers. (1997). What are Volcano Hazards?: USGS Fact Sheet 002-97. Retrieved from:
http://vulcan.wr.usgs.gov/Glossary/VolcWeather/description_volcanoes_and_weather.html
Robock, A. Introduction: Mount Pinatubo as a Test of Climate Feedback Mechanisms. Retrieved
from: http://climate.envsci.rutgers.edu/pdf/VEAChapter1_Robocknew.pdf
Rosenberg, M. (August 2007). Mount Pinatubo Eruption: The Volcanic Mount Pinatubo Eruption
of 1991 that Cooled the Planet. Retrieved from:
http://geography.about.com/od/globalproblemsandissues/a/pinatubo.htm
Wolfe, J. (September 2000). Volcanoes and Climate Change. Earth Observatory. Retrieved
from: http://earthobservatory.nasa.gov/Features/Volcano/
(April 2009). Greenhouse Gases Continue to Climb Despite Economic Slump, Carbon Dioxide,
Methane Increased in 2008. Retrieved from:
http://www.noaanews.noaa.gov/stories2009/20090421_carbon.html
http://www.physicalgeography.net/fundamentals/7y.html
http://www.ngdc.noaa.gov/hazard/stratoguide/img/aerosol.gif
http://www.innovations-report.de/html/berichte/geowissenschaften/bericht-17078.html
http://www.agu.org/pubs/crossref/2006/2005JD006286.shtml
4. Gas Formation
E>A>L>B
Magma from volcanoes contains dissolved
gasses that can either be released into the
atmosphere during eruptions or released while
the magma is still underground or rising to the
surface. Deep within Earth’s surface, volcanic
gasses are dissolved in molten rock. When
magma starts to rise to Earth surface, small gas
bubbles form and expand. Once they reach the
surface the bubbles increase in number and size.
Throughout a volcanoes life, gasses may be
released into the atmosphere from the soil,
hydrothermal systems, and volcanic vents and
from fumaroles. Fumaroles are vents where
volcanic gas can escape and they can be located
in tine cracks, long fissures and even on the
surface of lava flows. According to Myers, ninety
prevent of all gas emitted by volcanoes is water
vapor which comes from heated ground water from either rain fall or streams. Volcanic gasses
can rise many miles into earth’s atmosphere and be blown all the way around the world.
Besides for water vapor, volcanic gas contains other natural elements like hydrogen, sulfur,
fluorine, chlorine, hydrogen and compounds like carbon dioxide, sulfur dioxide and carbon
monoxide. In high concentrations fluorine or F, can soak into ash particles that later fall onto the
lithosphere. These particles can soak into the Earth’s water s supplies and not only harm the
vegetation but also the organisms that feed upon it. To humans it can cause skin irritation,
conjunctivitis, degeneration of the bone and the rotting of teeth. Excess fluorine results in a
significant cause of death and injury in livestock during ash eruptions. Sulfur dioxide or SO2
can also cause harm to vegetation because it corrodes the lithosphere by combining with water
in the atmosphere, thus forming acid rain. The eruption of Mt. Pinatubo in 1991 released 3-5 km
3
of dacite magma and expelled roughly 17 million tons of sulfur dioxide into the stratosphere.
Carbon dioxide or CO2 is also a volcanic gas, it is heavier than air and when it accumulates in
low areas in high concentrations it can be deadly to most organisms. It is extremely imperative
to avoid small depressions and low areas because they can trap carbon dioxide. The boundary
between the lethal carbon dioxide and
healthy air is very rigid, sadly even a
single step either way may be the
difference between living and dying.
Even though volcanic gas is comprised of
a lot of carbon dioxide (it gives off about
110 million tons per year) it is not
abundant enough to play any part in the
greenhouse effect that humans are
contributing to (roughly about 10 billion
tons per years).
Figure 7y-6: The following satellite image shows the distribution of Mount Pinatubo's sulfur
dioxide and dust aerosol plume (red and yellow areas) between June 14 and July 26, 1991.
References:
Doukas, M.P., Gerlach, T.M., Kessler, R. & McGee, K.A. (May 2009). Impacts of Volcanic
Gases on Climate, the Environment, and People. U.S. Geological Survey Open-File Report 97262. Retrieved from: http://pubs.usgs.gov/of/1997/of97-262/of97-262.html
Myer. ( 1997). What are Volcano Hazards?: USGS Fact Sheet 002-97. Retrieved from:
http://vulcan.wr.usgs.gov/Glossary/VolcWeather/description_volcanoes_and_weather.html
http://volcano-pictures.info/glossary/fumarole.html
http://volcanoes.usgs.gov/hazards/gas/index.php
http://volcanology.geol.ucsb.edu/gas.htm
http://www.sciencemaster.com/jump/earth/gases.php
5. Vog
E>A>B
Volcanic smog or vog, forms when sulfur dioxide found in magma reacts with atmospheric
moisture. You cans see it in the air as haze around a volcano and is caused by combination of
wind, weather and volcanic activity. Vog can cause severe respiratory problems, headaches,
sore throats and watery eyes.
References:
Heliker. (1997). Living on Active Volcanoes -- The Island of Hawai'i: USGS Fact Sheet 074-97.
Retrieved from:
http://vulcan.wr.usgs.gov/Glossary/VolcWeather/description_volcanoes_and_weather.html
http://hawaii.gov/gov/vog
6. Ozone and Sulfuric Acid
E>A
During the one and a half years after the eruption of Mt Pinatubo in 1991, the levels in ozone in
the stratosphere decreased. Ozone or O3 is an inorganic molecule found in the atmosphere and
is produced when extreme sunlight in the stratosphere specifically breaks down oxygen
molecules or on into two extremely and highly reactive atoms of oxygen, or O. The O2 (oxygen)
molecules and the O (oxygen) atoms bond to form ozone. The stratosphere is the outer region
of Earths atmosphere that extends 7 to 25 miles above the Earth’s surface. The outermost
region of the stratosphere contains the ozone layer. The levels in ozone dropped after the 1991
Mt. Pinatubo eruption because of the reaction between the volcanoes release of the gas sulfur
dioxide and the ozone. The first major injection of sulfur dioxide into the atmosphere was on
June 30, 1991.
References:
http://www.geology.sdsu.edu/how_volcanoes_work/climate_effects.html
http://svs.gsfc.nasa.gov/stories/pinatubo_20010618/images.html