During the second mission of the Cryogenic Spectrometers and Telescopes for the Atmosphere (CRISTA) in August 1997 considerable and highly variable cloud cover in the stratosphere was seen over Antarctica. Two large areas of polar stratospheric clouds (PSC) could be observed. One region of PSCs near the vortex edge was caused by a meteorological situation as it is typical for an ozone minihole event and dissolved within two days. The temperature dependence of the HNO3 measured by CRISTA suggests that outside of their center the clouds consists of type I particles. However, a further discrimination between nitric acid trihydrate (NAT) or supercooled ternary solutions (STS) is not possible, due to the uncertainties in the meterological temperatures and the amount of water vapor. ¿ 2001 American Geophysical Union