  The paper proposes a model of deep and prolonged eclipses of young stars of
the UX~Ori type. Some of these events continue for decades and existing models
cannot explain them. Our paper shows that such eclipses can be caused by the
falling of gas and dust clump from the remnants of the protostellar cloud onto
the protoplanetary disk. The disturbance in the disk caused by the fall of the
clump leads to a surge in the accretion activity of the star and, as a
consequence, to an increase in the disk wind. If the circumstellar disk is
tilted at a slight angle to the line of sight, then dust raised by the wind
from the surface of the disk can cause a strong decrease in the star's
brightness, which can last for decades.
