  Ultra-hot Jupiters are the hottest exoplanets discovered so far. Observations
begin to provide insight into the composition of their extended atmospheres and
their chemical day/night asymmetries. Both are strongly affected by cloud
formation. We explore trends in cloud properties for a sample of five giant gas
planets: WASP-43b, WASP-18b, HAT-P-7b, WASP-103b, and WASP-121b. This provides
a reference frame for cloud properties for the JWST targets WASP-43b and
WASP-121b. We further explore chemically inert tracers to observe geometrical
asymmetries, and if the location of inner boundary of a 3D GCM matters for the
clouds that form. The large day/night temperature differences of ultra-hot
Jupiters cause large chemical asymmetries: cloud-free days but cloudy nights,
atomic vs. molecular gases and respectively different mean molecular weights,
deep thermal ionospheres vs. low-ionised atmospheres, undepleted vs enhanced
C/O. WASP-18b, as the heaviest planet in the sample, has the lowest global C/O.
The global climate may be considered as similar amongst ultra-hot Jupiters, but
different to that of hot gas giants. The local weather, however, is individual
for each planet since the local thermodynamic conditions, and hence the local
cloud and gas properties, differ. The morning and the evening terminator of
ultra-hot Jupiters will carry signatures of their strong chemical asymmetry
such that ingress/egress asymmetries can be expected. An increased C/O ratio is
a clear sign of cloud formation, making cloud modelling a necessity when
utilizing C/O (or other mineral ratios) as tracer for planet formation. The
changing geometrical extension of the atmosphere from the day to the nightside
may be probed through chemically inert species like helium. Ultra-hot Jupiters
are likely to develop deep atmospheric ionospheres which may impact the
atmosphere dynamics through MHD processes.
