A grid of ATLAS9 model atmospheres has been computed, spanning Teff in 3500--8000K, log.g in 0.0--5.0, [Fe/H] in -4.0--0.0, [{alpha}/Fe] in -0.08--1.2. These parameters are appropriate for stars in the red giant branch, subgiants, and the lower main sequence. The main difference from a previous, similar grid (Castelli & Kurucz 2003, "Modelling of Stellar Atmospheres", 210, astro-ph/0405087) is the range of [{alpha}/Fe] values. A grid of synthetic spectra, calculated from the model atmospheres, is also presented. The fluxes are computed every 0.02{AA} from 630nm to 910nm. The microturbulent velocity is given by a relation to the surface gravity. This relation is appropriate for giants, but not for subgiants or dwarfs. Therefore, caution is urged for the synthetic spectra with log.g>3.5.