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Small-scale umbral brightenings (SSUBs), umbral microjets, spikes or shortdynamic fibrils (SDFs), and umbral dark fibrils are found in any observation ofthe chromosphere with sufficient spatial resolution. We study the spatial andspectral co-evolution of SDFs, SSUBs, and umbral flashes in Ca II 8542 spectralprofiles. We produce models that generate the spectral profiles for all classesof features using non-LTE radiative transfer with a recent version of theNICOLE inversion code. We find that both bright (SSUBs) and dark (SDFs)structures are described with a continuous feature in the parameter space thatis distinct from the surroundings even in pixel-by-pixel inversions. We find aphase difference between such features and umbral flashes in both invertedline-of-sight velocities and timing of the brightenings. For umbral flashesthemselves we resolve, for the first time in inversion-based semi-empiricalmodelling, the pre-flash downflows, post-flash upflows, and the counter-flowspresent during the umbral flash phase. We further present a simpletime-dependent cartoon model that explains the dynamics and spectral profilesof both fine structure, dark and bright, and umbral flashes in umbralchromospheres. Conclusions. The similarity of the profiles between thebrightenings and umbral flashes, the pattern of velocities obtained from theinversions, and the phase relationships between the structures all lead us toput forward that all dynamic umbral chromospheric structures observed to thisdate are a locally delayed or locally early portion of the oscillatory flowpattern that generates flashes, secondary to the steepening large-scaleacoustic waves at its source. Essentially, SSUBs are part of the same shock ormerely compression front responsible for the spatially larger umbral flashphenomenon, but out of phase with the broader oscillation.

Umbral chromospheric fine structure and umbral flashes modelled as one: the corrugated umbra