$250,000$K. The dark upflows were found to rise at constant velocity of $\sim 20$kms$^{-1}$. Often these plumes would separate from the cavity forming bubbles inside the prominence material.

![Panel (a) shows a quiescent prominence observed on the 3-Oct-2007 at 04:16UT. Panel (b) shows a zoom-in of the region in the box in panel (a). The plume and the bright prominence plasma above it are clearly visible.[]{data-label="prom"}](figure1_a.eps "fig:"){height="8cm"} ![Panel (a) shows a quiescent prominence observed on the 3-Oct-2007 at 04:16UT. Panel (b) shows a zoom-in of the region in the box in panel (a). The plume and the bright prominence plasma above it are clearly visible.[]{data-label="prom"}](figure1_b.eps "fig:"){height="8cm"}

[@BERG2010] hypothesized that the observed upflows were caused by the magnetic Rayleigh-Taylor instability, as a mixed mode perturbation with an interchange mode ($k$ perpendicular to $B$) and an undular mode ($k$ parallel to $B$), in the high Atwood number limit \[$A=(\rho_+ - \rho_-)/(\rho_+ + \rho_-) \rightarrow 1$\], where $k$ is the wave number, $\rho_+$ is the density of the region above the contact discontinuity and $\rho_-$ is the density of the below the contact discontinuity. [@RYU2010] described how the theoretically predicted growth rates and behaviour for the magnetic Rayleigh-Taylor instability well match the observations 