  We depict and analyze a new effect for wavepackets falling freely under a
barrier or well. The effect appears for wavepackets whose initial spread is
smaller than the combination $\ds \sqrt{\frac{l_g^3}{|z_0|}}$, between the
gravitational length scale $\ds l_g = \frac{1}{(2 m^2 g)^{1/3}}$ and the
initial location of the packet $z_0$. It consists of a diffractive structure
that is generated by the falling and spreading wavepacket and the waves
reflected from the obstacle. The effect is enhanced when the Gross-Pitaevskii
interaction for positive scattering length is included. The theoretical
analysis reproduces the essential features of the effect. Experiments emanating
from the findings are proposed.
