Mist Opportunity: A Journey to the Arctic and Sahara to Learn How Dust Contributes to Cloud Formation [Slide Show]
A trip to Iceland and a flight over the Sahara Desert help an atmospheric scientist study dust particles that seed clouds
Credits: COURTESY OF SAMUEL DORSI
Rocky features in the desert helped make the flight's low altitude apparent. Collecting natural samples of potential cloud nucleation particles is vital to replicating and studying the process in the lab, Baustian explains. This work will help scientists understand how clouds and cloud formation affect global temperature and climate.
INTO THE DUST STORM
Visibility was extremely low during the most intense part of the dust storm. Above the desert, the cabin temperatures rose to approximately 37 degrees Celsius, Baustian says.
Baustian has the role of dust collector on this trip. On flights below 300 meters, which can be bumpy, all passengers need seat belts, but the person gathering samples needs to be mobile, so Baustian wore a harness. "You can imagine how much turbulence there is when you are flying 250 feet above the desert and all that heat radiates off the surface," she says.
Specially equipped airplanes are also part of cloud research. In June 2012 Baustian hopped onboard this British BAe-146 research aircraft for a flight through a Saharan dust storm (Like Iceland, the desert holds cloud clues). The aircraft has special inlets that collect dust aerosols. The expedition was part of an international climate research program, called the Fennec campaign.
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NEXT STOP, THE LAB
The researchers' hotel room bathtub briefly held all the bagged Icelandic sediment. The samples were shipped to Ben Murray's lab at the University of Leeds, where Baustian is a postdoctoral researcher. "We essentially try to replicate upper tropospheric conditions in the lab," Baustian says. They will suspend the dust in cloud droplets and "observe the temperatures at which they freeze."
DISTANT ICE FLOWING
An outlet glacier that drains the Vatnajökull ice cap pushes its way past craggy mountains. The ice cap is the largest glacier in Europe.
REMNANTS OF DESTRUCTION
"Volcanic eruptions under glaciers can release vast quantities of water," Dorsi wrote in a blog post chronicling the trip. "Evidence of past destruction from these floods was everywhere: sheared wooden bridge pylons, abandoned highway beds and discarded three-foot-wide steel I-beams bent like noodles."
TOOLS OF THE TRADE
Sample-collection tools included a bucket and hand trowels. In each location they dug test holes to find the finest sediment. In the lab Baustian will segregate particles by size and isolate the smallest grains for her cloud-formation experiments.
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Baustian collected water and soil samples near a swiftly flowing glacial river. To reach this sample site, Dorsi and Baustian hiked across several hundred meters of riverbed, strewn with volcanic rocks and dirt.
ICE AND FIRE Iceland's black volcanic rocks are ground to a fine dust by flowing glaciers. Rivers of meltwater carry that dust as sediment toward the ocean, and periodic floods triggered by volcanic eruptions sculpt the floodplains. Strong winds off the glaciers lift particles smaller than 10 microns into the air. Those airborne dust plumes can travel hundreds of kilometers off the coast and are visible from space, Baustian says.
FIRST SAMPLE Samuel Dorsi holds this "contingency sample," which the researchers collected at the first small glacial outwash plain they found, to assure that they would have at least one sample even if unexpected events cut their trip short—astronauts had taken similar precautions after landing on the moon.
GLIMPSE OF SUN
This glacial floodplain in Iceland contains fine-grained sediment that when airborne may play a role in cloud formation. Kelly Baustian, an atmospheric scientist at the University of Leeds School of Earth and Environment in England, and her colleague Samuel Dorsi traveled here this past November on a research trip to collect samples. The route took them along the Iceland’s southern coast, where they saw this rare moment of sun breaking through the clouds.
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