  High spectral resolution observations of Venus were obtained with the TEXES
instrument at NASA's Infrared Telescope Facility. These observations focus on a
CO$_2$ absorption feature at 791.4 cm$^{-1}$ as the shape of this absorption
feature can be used to retrieve the vertical temperature profile in Venus'
mesosphere. By scan-mapping the planet, we are able to build up
three-dimensional temperature maps of Venus' atmosphere, covering one
Earth-facing hemisphere and an altitude range of 60--83 km. A temperature map
from February 12, 2019 clearly shows the three-dimensional structure of a
planetary-scale thermal wave. This wave pattern appears strongest in the
mid-latitudes of Venus, has a zonal wavenumber of 2--4 and the wave fronts tilt
eastward with altitude at an angle of 8--15 degrees per km. This is consistent
with a thermal tide propagating upwards from Venus' upper cloud decks.
Ground-based observations provide the opportunity to study Venus' temperature
structure on an ongoing basis.
