HI high-velocity clouds (HVCs) have so far only be seen in the
 21cm line of atomic hydrogen and as absorption features in optical
 spectra towards distant quasars. No firm estimates on their distances
 exist. Therefore almost nothing is known about their chemical
 composition and physical parameters.
 Despite several attempts no CO has been found in HVCs. Therefore
 the dominant cooling line for the clouds should be
 the 157.7micron [CII] fine structure line which we want to
 study towards an HI high-velocity cloud which is likely to
 interact with an intermediate velocity cloud.
 Both clouds are positionally anticorrelated on the sky with
 almost no overlap between them. This unique positioning on the sky
 makes it possible to observe the [CII] line of the HVC without
 applying the time consuming Fabry-Perot mode of the LWS which
 provides high frequency resolution.
 To get information on the interstellar radiation field of both
 clouds we want to observe two positions, one towards the IVC and
 one towards the HVC. The comparison of both positions will
 then give hints on the composition of the HVC and thus on its
 possible origin.