  The study of exoplanet atmospheres showed large diversity compared to the
planets in our solar system. Especially Jupiter type exoplanets orbiting their
host star in close orbits, the so-called hot and ultra-hot Jupiters, have been
studied in detail due to their enhanced atmospheric signature. Due to their
tidally locked status, the temperature difference between the day- and
nightside triggers atmospheric winds which can lead to various fingerprints in
the observations. Spatially resolved absorption lines during transit such as
sodium (Na) could be a good tracer for such winds. Different works resolved the
Na$^-$ absorption lines on different exoplanets which show different line
widths. Assuming that this could be attributed to such zonal jet streams, this
work models the effect of such winds on synthetic absorption lines. For this,
transiting Jupiter type planets with rotational velocities similar to hot and
ultra-hot Jupiter are considered. The investigation shows that high wind
velocities could reproduce the broadening of Na-line profiles inferred in
different high-resolution transit observations. There is a tendency that the
broadening values decrease for planets with lower equilibrium temperature. This
could be explained by atmospheric drag induced by the ionization of alkali
lines which slow down the zonal jet streams, favoring their existence on hot
Jupiter rather than ultra-hot Jupiter.
