  The problem of disk accretion onto the surface of a neutron star with a weak
magnetic field at a luminosity exceeding several percent of Eddington is
reduced to the problem of the braking of a hypersonic flow with a velocity that
is 0.4-0.5 of the speed of light above the base of the spreading layer -- a
dense atmosphere made up of previously fallen matter. We show that turbulent
braking in the Prandtl-Karman model with universally accepted coefficients for
terrestrial conditions and laboratory experiments and a ladder of interacting
gravity waves in a stratified quasi-exponential atmosphere at standard
Richardson numbers lead to a spin-up of the massive zone that extends to the
ocean made up of a plasma with degenerate electrons. Turbulent braking in the
ocean at the boundary with the outer solid crust reduces the rotation velocity
to the solid-body rotation velocity of the star. This situation should lead to
strong heating of deep atmospheric layers and to the switch-off of the
explosive helium burning mechanism. Obviously, a more efficient mechanism for
the dissipation of a fast azimuthal flow in the atmosphere should operate in
X-ray bursters. We show that a giant solitary gravity wave in the atmosphere
can lead to energy dissipation and to a sharp decrease in azimuthal velocity in
fairly rarefied atmospheric layers above the zone of explosive helium burning
nuclear reactions. We discuss the reasons why this wave, that has no direct
analog in the Earth's atmosphere or ocean, appears and its stability. We pose
the question as to whether neutron stars with massive atmospheres, spun up to
high velocities by accreting matter from a disk, can exist among the observed
Galactic X-ray sources.
