A model of the prolate chromosphere formation at the solar minimum

Detailed observations in different chromospheric lines of a solar diameter in polar and equatorial directions showed that the polar chromosphere at the minimum phase of solar cycle looks more extended than the low-latitude chromosphere. We propose a simple geometric model to explain the effect of the prolateness of the solar chromosphere. A specific dynamical part of the solar atmosphere above the 2 Mm level is assumed to be a mixture of moving up and down jets of chromespheric matter with the coronal plasma between them. Due to the dynamic nature of this layer, the magnetic field is considered to play a very important role in the density distribution with the height, guiding the mass flows along the field lines. The difference of the magnetic-field topology in the polar and the equatorial regions leads to different heights of the chromospheric limb.