  The Antarctic winter atmosphere minimal temperature and pressure series
reveal that $CO_2$ phase shift (deposition) is possible in some extreme cases,
even leading to possible $CO_2$ snow phenomenon at Vostok Antarctic station and
in other near South Pole regions. A hypothesis has been formulated that stable
$CO_2$ snow cover might have formed in Earth past which may influence
interpretation of glacial chronology records. This effect may also manifest in
other minor gases. Its global climate role is discussed.
