Nacreous Clouds or Polar Stratospheric
This type of cloud
is responsible for the destruction of atmospheric
ozone. They create conditions that release
chlorine from chlorofluorocarbons (CFC's)
which reacts with and destroys ozone throughout
the Antarctic winter when these clouds develop,
they are maintained by the "polar vortex"
a circumpolar wind that isolates Antarctic
weather from the rest of the world so giving
them longer to have their effect on the
trapped ozone being depleted.
There are two kinds of Polar
Stratospheric Clouds, those that form at
about -78°C (-108°F)
contain nitric acid and water crystals and
possibly sulphuric acid, while those
that start to form at about -85°C (-121°F) have
more water crystals.
23/08/2009 15.32 - McMurdo Antarctica.
Our Lady of the Snows
Shrine, a.k.a. Roll Cage Mary on the lower
hill to the left.