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Some evidences of wind variability and velocity stratification in theextended atmosphere has been found in the spectra of the supergiant V340 Ser(=IRAS 17279$-$1119) taken at the 6-m BTA telescope with a spectral resolutionR$\ge$60000. The H$\alpha$ line has a P Cyg profile whose absorption component(V=+34 km/s) is formed in the upper layers of the expanding atmosphere close tothe circumstellar environment. For four dates the mean velocity has beenderived from the positions of 300-550 symmetric metal absorptions with anaccuracy better than $\pm0.1$ km/s: Vr=59.30, 60.09, 58.46, and 55.78 km/s. Alot of low-excitation metal lines have an inverse P Cyg profile. The meanpositions of their emission components, Vr=46.3$\pm$0.4 km/s, differsystematically from the velocity inferred from symmetric absorptions,suggesting the presence of a velocity gradient in the supergiant extendedatmosphere. The multicomponent profile of the NaI D-lines contains theinterstellar, Vr=-11.2 km/s, and circumstellar, Vr=+10 km/s, components and thecomponent forming in the upper atmospheric layers, Vr=+34.0 km/s. The meanvelocity from 20-30 diffuse interstellar bands (DIBs) identified in thespectra, Vr(DIBs)=-11.6$\pm0.2$ km/s, agrees with the velocity frominterstellar NaI and KI components. The equivalent width of the oxygen tripletW(7774)=1.25 A corresponds to an absolute magnitude of the starMv$\approx-4.6^m$, which, taking into account the total(interstellar+circumstellar) extinction, leads to a distance to the stard$\approx$2.3 kpc.

High-resolution optical spectroscopy of the post-AGB supergiant V340 Ser (=IRAS 17279$-$1119)