Does the sun have a full-time chromosphere?

The successful modeling of the dynamics of H-2v bright points in the nonmag netic chromosphere by Carlsson & Stein gave as a by-product a part-time chr omosphere lacking the persistent outward temperature increase of time-avera ge empirical models, which is needed to explain observations of UV emission lines and continua. We discuss the failure of the dynamical model to accou nt for most of the observed chromospheric emission, arguing that their mode l uses only about 1% of the acoustic energy supplied to the medium. Chromos pheric heating requires an additional source of energy in the form of acous tic waves of short period (P < 2 minutes), which form shocks and produce th e persistent outward temperature increase that can account for the UV emiss ion lines and continua.