  Flaring activity in blazars can last for vastly different time-scales, and
may be the result of density enhancements in the jet flow that result from the
intrusion of an interstellar cloud into the jet. We investigate the lightcurves
expected from the ablation of gas clouds by the blazar jet under various cloud
and jet configurations. We derive the semi-analytical formulae describing the
ablation process of a hydrostatic cloud, and perform parameter scans of
artificial set-ups over both cloud and jet parameter spaces. We then use
parameters obtained from measurements of various cloud types to produce
lightcurves of these cloud examples. The parameter scans show that a vast zoo
of symmetrical lightcurves can be realized. Both cloud and emission region
parameters significantly influence the duration, and strength of the flare. The
scale height of the cloud is one of the most important parameters, as it
determines the shape of the lightcurve. In turn, important cloud parameters can
be deduced from the observed shape of a flare. The example clouds result in
significant flares lasting for various time scales.
