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 .
Several phenomena occur simultaneously , namely , abnormal granulation , separation of opposite-polarity legs , and brightenings at chromospheric heights .
However , 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 .
There is a clear coincidence between the emergence of horizontal magnetic field patches and the formation of the dark bubble .
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 ^ { -1 } and expands at a horizontal speed of 4 km s ^ { -1 } .
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 ^ { -1 } .
The maximum separation attained by the magnetic legs is 6 \farcs 6 .
From an inversion of the observed Stokes spectra with the SIR code we find maximum photospheric field strengths of 480 G and inclinations of nearly 90 ^ { \circ } in the magnetic bubble interior , along with temperature deficits of up to 250 K at \log \tau = -2 and above .
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 .