The equations governing the motion and thermodynamic state of a gas that absorbs energy from an electromagnetic field, interfering with itself within that gas, are linearized and solved in closed form. The dependence of the solution on the geometrical configuration of the gas enclosure, on the polarization state of the incident electromagnetic field, and on the various time constants of the system are derived. The relevant time constants of the system include the pulse duration of the electromagnetic field, the characteristic times for photon absorption, and for transfer of the absorbed energy into translational energy modes, the times associated with the diffusion of heat and vorticity, and the time required for pressure pulses to transit the distance between the laser‐induced grating planes. The space and time variations of the mass density of a mixture of gaseous ammonia and nitrogen resulting from energy absorbed from a pulsed carbon dioxide laser are calculated to illustrate the characteristics of the solution.