Speeds of vertical flows in quiescent solar filaments are typically much le
ss than the local Alfven speed. This is why the flows in filament barbs can
be modeled by perturbing a magnetostatic solution describing a balance bet
ween the Lorentz force, gravity, and gas pressure in a barb. This approach
explains why some of the flows are neither aligned with the magnetic field
nor controlled by gravity. Both the observed upflows and the magnetic field
dips in barbs are likely to be caused by photospheric magnetic reconnectio
n.