Atmospheric turbulence limits the angular resolution of ground-based optical telescopes. The daytime turbulence conditions for solar observations are stronger and more complicated than the turbulence observed at night. The Baikal Astrophysical Observatory is the site of the 1-m Large Solar Vacuum Telescope (LSVT) located near Lake Baikal (East Siberia, Russia), which is the largest freshwater lake in the world. The region hosts unique weather regimes and natural phenomena, including local winds and giant ice rings. Because the LSVT has ongoing and planned programmes in adaptive optics (AO), statistical knowledge of atmospheric turbulence and wind speed distributions is essential for designing and optimizing AO systems. We present the first seasonal study of the vertical distribution of wind speed and daytime optical turbulence conditions at the Baikal Astrophysical Observatory. Site measurements of the daytime Fried parameter were collected using the Shack–Hartmann wavefront sensor in the LSVT AO system. Reanalysis data from the National Centers for Environmental Prediction (NCEP) and the National Centers for Atmospheric Research (NCAR) were used to characterize the wind speed distribution. The results demonstrate seasonal variation in both solar seeing and wind speed profile. The strongest wind speed was detected in winter and in November, while the weakest wind speed occurred during summer. The strongest daytime turbulence conditions were observed in the winter. The best solar seeing β₀ ≈ 1 arcsec was detected in the summer.

Results of synchronous optical and meteorological measurements of Fried’s coherence length at the Large Solar Vacuum Telescope are presented. A decrease in this parameter in winter time is revealed. Spectra of wind speed and temperature inhomogeneities are studied during measurements of the Fried’s length.

The paper focuses on the investigations of the optical turbulence structure. The distributions of the repeatability of the structure characteristic of the air refractive index are obtained. A scenario of decreasing the intensity of the optical turbulence in the summer is discussed. Numerical estimates of this scenario are given. Using classical methods of wavefront analysis, the results of the first studies of the vertical structure of atmospheric turbulence at the Baykal astrophysical observatory site are presented.

New results obtained within Russian Science Foundation Project no. 15-19-20013 are presented. The project was started in the middle of 2015 and is aimed at the solution of actual problems of the development of the optoelectronic industry using adaptive optics for astronomy, laser, and other applications. The progress in the development of the up-to-date adaptive optics system for the largest Russian solar telescope, i.e., the 1-m Big Solar Vacuum Telescope of the Baikal Astrophysical Observatory, is described.

Knowledge of the turbulence spectra is of interest for describing atmospheric conditions as applied to astronomical observations. This article discusses the deformations of the turbulence spectra with heights in a wide range of scales at the sites of the Maidanak and Suffa observatories. It is shown that the energy of baroclinic instability is high at the sites of these observatories and should be taken into account in the calculations of the refractive index structure constant $C_n^2$.