March
5, 2007 Tiny lab versions of
12-foot tall
snow spikes that form naturally on some high mountain glaciers may
someday help
scientists mitigate the effects of global warming in the Andes,
according to a CU-Boulder physics
Assistant
Professor Meredith Betterton said the spikes, known as penitentes, are
shaped
when concentrated rays of sunlight evaporate snow from low spots on
glacier
fields in a process known as sublimation. The lab studies confirm that
the low
spots, or troughs, deepen as intense sunlight strikes them, sculpting
penitentes by the hundreds of thousands on some glaciers, she said. Some scientists have
predicted
that penitentes might help put the brakes on shrinking glaciers in a
warming
climate by blocking sunlight that might otherwise be absorbed by
glacial
surfaces, said Betterton. She gave a presentation on penitentes at the
March
Meeting of the American Physical Society in "The key piece of
physics
here is that the dips in the snow absorb more reflected light, which
drops the
snow height and helps to form the penitentes," she said. "One big
question is how penitentes will fare in a warming world." Betterton, along
with colleagues
Vance Bergeron and Charles Berger from Ecole Normale Superieure
research
laboratories in The research team
put a block of
snow in a horizontal freezer in The study confirmed
previous
theories that penitentes grow when sunlight in cold, dry air in the
high
mountains strikes snow patches and transforms them directly into water
vapor,
she said. Mathematical models developed by Betterton indicate
microscopic
penitentes begin merging with each other, or "coarsening," early in
the sublimation process, growing both taller and wider over time. The research has
applications for
understanding and even mitigating global warming, since Andean
penitentes shade
large areas of glacial surfaces, possibly cooling them and slowing the
rate of
ice loss, she said. Some scientists believe warming temperatures could
trigger
the eventual destruction of vast fields of penitentes and hasten
glacier
melting, "which would be disastrous for Argentinean and Chilean regions
that depend on runoff for water supplies," said Betterton. Betterton and her
colleagues took
the research a step further, sprinkling the sprouting lab penitentes
with a
fine layer of carbon soot to simulate pollutants known to be
accumulating on
some glaciers around the globe. Such carbon-based pollutants have been
found to
increase melting rates on glaciers by causing the ice to absorb more
sunlight
and heat up, she said. The team found that
small amounts
of soot sprinkled on the snow in the lab appeared to accelerate
penitente
formation. "One worry that scientists have is that without penitentes,
some of these Andean glaciers will melt more quickly," she said. "It
may well be that adding a small layer of dirt to the surface of these
glaciers
could help to preserve them." The penitente
research effort
also has implications for the microelectronic industry, she said.
Precisely
shaped micro-penitentes formed by laser beams could lead to the
development of
solar energy cells that trap light more efficiently.
Recommend this Article to a Friend Back to: News |
Subscribe to the Earth Observatory About the Earth Observatory Contact Us Privacy Policy and Important Notices Responsible NASA Official: Lorraine A. Remer Webmaster: Goran Halusa We're a part of the Science Mission Directorate |