The colors represent the density of particles that make up the wind. Particles from the atmosphere can be blown away by UV-radiation and so escape the doom of the black hole.
Arrows represent the UV-driven wind of particles around the accretion disk of a black hole.
A first wind, from the inner regions of the accretion disk, pushes matter up and away from the plane of the accretion disk. But with the black hole's gravity pulling it back and X-ray radiation stripping away electrons, the wind just barely makes it to the middle regions of the accretion disk. As the particles fall back to this middle region, however, they shield the outer region from the X-ray radiation produced very close to the black hole. This shielding in the outer disk allows the gas that is present there to keep their electrons. In this image, we see the density of particles that can fly off the accretion disk of a black hole.