The meaning of halo

1, the ghost image diffuses from the edge of the developed image. A halo with blurred edges.

2. Photography means that in the process of exposure shooting, when strong light is projected on the film, it is reflected to the surface of the film base through the film emulsion, thus causing image blur.

Halo refers to the process of exposure shooting, when strong light is projected on the film, it is reflected to the surface of the film base through the film emulsion, thus causing image blur. In order to prevent this phenomenon, sometimes a colored layer is coated between the film base and the emulsion layer, which can be removed during development, or a gray layer is coated on the film base, which is called an anti-blooming layer.

Interpretation by reference:

Mao Dun's Midnight 14: "The headlights in the room went out, leaving only the lights on the table with a yellow halo."

Xu Chi's Tale of Huangshan Mountain: "It has a colorful halo like a picture frame, and a mirror in the middle can show a human figure."

Halo phenomenon: a group of optical phenomena in the form of rings, arcs, columns or bright spots caused by the refraction or reflection of light by ice crystals suspended in the atmosphere (cirrus clouds, "diamond sand", etc.). ).

22 halo (called small halo in the past, but in the folk, 22 halo is considered as one of the signs before storm warning) is the most common halo phenomenon. A halo is a white or nearly white luminous ring with a radius of 22, and the light source (sun or moon) is located in its center. Its inner burr is red, and in some rare cases, its outer burr is purple. The sky in the halo is obviously darker than other places. No matter where it is in the sky, the radius of the halo is always 22. Depending on the clouds, sometimes only a part of the whole circle can be seen. Want to know how to quickly and accurately verify the halo radius? Identification coup: straighten your arms and open your fingers. The angle from your thumb to the tip of your little finger is about 20 degrees. Cover the sun with the tip of your thumb, and you will find a halo of 22 near your little finger!