  Seeley and Wordsworth (2021) showed that in small-domain cloud-resolving
simulations the pattern of precipitation transforms in extremely hot climates
($\ge$ 320 K) from quasi-steady to organized episodic deluges, with outbursts
of heavy rain alternating with several dry days. They proposed a mechanism for
this transition involving increased water vapor absorption of solar radiation
leading to net lower-tropospheric radiative heating. This heating inhibits
lower-tropospheric convection and decouples the boundary layer from the upper
troposphere during the dry phase, allowing lower-tropospheric moist static
energy to build until it discharges, resulting in a deluge. We perform
cloud-resolving simulations in polar night and show that the same transition
occurs, implying that some revision of their mechanism is necessary. We show
that episodic deluges can occur even if the lower-tropospheric radiative
heating rate is negative, as long as the magnitude of the upper-tropospheric
radiative cooling is about twice as large. We find that in the episodic deluge
regime the mean precipitation can be inferred from the atmospheric column
energy budget and the period can be predicted from the time for radiation and
reevaporation to cool the lower atmosphere.
