  High spectral resolution transmission spectroscopy is a powerful tool to
characterize exoplanet atmospheres. Especially for hot Jupiters, this technique
is highly relevant, due to their high altitude absorption e.g. from resonant
sodium (Na I) and potassium (K I) lines. We resolve the atmospheric K
I-absorption on HD189733b with the aim to compare the resolved K I -line and
previously obtained high resolution Na I-D-line observations with synthetic
transmission spectra. The line profiles suggest atmospheric processes leading
to a line broadening of the order of 10 km/s for the Na I-D-lines, and only a
few km/s for the K I-line. The investigation hints that either the atmosphere
of HD189733b lacks a significant amount of K I or the alkali lines probe
different atmospheric regions with different temperature, which could explain
the differences we see in the resolved absorption lines.
