In the absence of an external field, the long-range alignment of a nematic liquid crystal (NLC) layer depends on surface anchoring by the bounding surfaces. A dynamic surface composed of an adsorbed amphiphilic monolayer at the nematic/aqueous interface anchors the nematic in both a temperature and surface pressure-dependent manner in response to the molecular organization of the monolayer. When composed of the azobenzene derivative 8Az3COOH anchoring is also shown to significantly depend on the isomeric (cis-trans) composition of the monolayer. Long-range alignment of the NLC layer is characterized by both the birefringence and director azimuth. Exhibited are isotropic 2D vapor and liquid phases, primarily dependent on surface pressure, and condensed mesophase domains with defined director azimuths at temperatures below 8-10 ^oC. Isomeric mixtures additionally exhibit a smectic C-like phase that anchors the NLC with varying degrees of birefringence and no set director azimuth. The phase diagram of an 8Az3COOH monolayer adsorbed at a nematic/aqueous interface is plotted as a function of the control parameters (temperature, surface concentration, and irradiation).