  Relationship between a surface pattern and vertical convections is studied in
a condition of Rayleigh-Taylor instability. The vertical convections change
with the case configuration and the aspect ratio r / h of the case, where r and
h show radius of case and height of the lighter solution. Fractal pattern is
observed at r < h, and cell pattern is formed at r > h. According to the
changes of the surface pattern, the vertical convection transfers to some
convections from coupled convections. This result shows that the surface
pattern is strongly influenced by the vertical convection.
