Interaction of light with a generalized thermo-acoustic field

The influence of the acoustic field and the field of free convection caused by a thermal source on the refractive index of light in a homogeneous continuous medium is considered. The corresponding expressions for both fields are given, allowing one to calculate the perturbations of the density of the medium, and, consequently, the perturbation of the refractive index of light caused by density perturbation Specific orders of magnitude of the velocity for free convection are given, the relative values of the density change, and also the expression for the Grashof number as a parameter of the flow intensity for free convection.