ESS5
Prof.
Jin-Yi Yu
Polar Stratospheric Clouds (PSCs)
qIn winter the polar stratosphere
is so cold (-80°C or below) that certain trace atmospheric constituents
can condense.
qThese clouds are called “polar stratospheric clouds”
(PSCs).
qThe particles that form typically
consist of a mixture of water and
nitric acid (HNO3).
qThe PSCs alter the chemistry of
the lower
stratosphere in two ways:
(1) by coupling between the odd nitrogen and chlorine cycles
(2) by providing surfaces on which heterogeneous reactions can
occur.
(Sweden,
January 2000; from NASA website)