  We study a granular-sized magnetic flux emergence event that occurred in NOAA
11024 in July 2009. The observations were made with the CRISP
spectropolarimeter at the Swedish 1 m Solar Telescope achieving a spatial
resolution of 0.14". Simultaneous full Stokes observations of the two
photospheric Fe I lines at 630.2 nm and the chromospheric Ca II 854.2 nm line
allow us to describe in detail the emergence process across the solar
atmosphere. We report here on 3D semi-spherical bubble events, where instead of
simple magnetic footpoints, we observe complex semi-circular feet straddling a
few granules. The most characteristic signature in these events is the
observation of a dark bubble in filtergrams taken in the wings of the Ca II
854.2 nm line. We can infer how the bubble rises through the solar atmosphere
as we see it progressing from the wings to the core of Ca II 854.2 nm. In the
photosphere, the magnetic bubble shows mean upward Doppler velocities of 2
km/s. In about 3.5 minutes it travels some 1100 km to reach the mid
chromosphere, implying an average ascent speed of 5.2 km/s. To aid the
interpretation of the observations, we carry out 3D numerical simulations of
the evolution of a horizontal, untwisted magnetic flux sheet injected in the
convection zone, using the Bifrost code. The computational domain spans from
the upper convection zone to the lower corona. In the modeled chromosphere the
rising flux sheet produces a large, cool, magnetized bubble. We compare this
bubble with the observed ones and find excellent agreement, including similar
field strengths and velocity signals in the photosphere and chromosphere,
temperature deficits, ascent speeds, expansion velocities, and lifetimes.
