  A new class of exoplanets is beginning to emerge: planets whose dayside
atmospheres more closely resemble stellar atmospheres as most of their
molecular constituents dissociate. The effects of the dissociation of these
species will be varied and must be carefully accounted for. Here we take the
first steps towards understanding the consequences of dissociation and
recombination of molecular hydrogen (H$_2$) on atmospheric heat recirculation.
Using a simple energy balance model with eastward winds, we demonstrate that
H$_2$ dissociation/recombination can significantly increase the day$-$night
heat transport on ultra-hot Jupiters (UHJs): gas giant exoplanets where
significant H$_2$ dissociation occurs. The atomic hydrogen from the highly
irradiated daysides of UHJs will transport some of the energy deposited on the
dayside towards the nightside of the planet where the H atoms recombine into
H$_2$; this mechanism bears similarities to latent heat. Given a fixed wind
speed, this will act to increase the heat recirculation efficiency;
alternatively, a measured heat recirculation efficiency will require slower
wind speeds after accounting for H$_2$ dissociation/recombination.
