  As progress towards real implementations of cryogenic high gradient normal
conducting accelerating cavities continues, a more mature understanding of the
surface physics in this novel environment becomes increasingly necessary. To
this end, we here focus on developing a deeper understanding of one cavity
figure of merit, the radiofrequency (RF) surface resistivity, $R_s$. A
combination of experimental measurements and theory development form the basis
of this work. For many cases, existing theory is sufficient but there are
nuances leading to systemic errors in prediction which we address here. In
addition, for certain cases there exist unexpected local minimum in $R_s$ found
at temperatures above 0K. We compare here several alternative models for RF
surface resistivity those which incorporate thin film like behavior which we
use to predict the location of the local minimum in surface resistivity. Our
experimental results focus on C-band frequencies for the benefit of several
future cryogenic linear accelerator concepts intended to operate in this
regime. To this end we have measured factor of $2.89\pm 0.05$ improvements in
quality factor at $77$K and $4.61\pm 0.05$ at 45K. We further describe the test
setup and cooling capabilities to address systematic issues associated with the
measurements as well as a comparison of RF cavity preparation and the
significant effect on $R_s$. Some implications of our measurements to linear
accelerators combined with the theoretical considerations are extended to a
wider range of frequencies especially the two additional aforementioned bands.
Additional possible implications for condensed matter physics studies are
mentioned.
