Green beam

Optical phenomenon, a green light flash in the time of the disappearance of the solar disk over the horizon (usually marine) or its appearance over the horizon. For observation of the green ray is required three conditions: an open horizon (in the desert, the tundra, the mountains or the sea in the absence of disturbances), the clean air and the horizon free from clouds, where the sunset or sunrise. To observe with the naked eye can be quite rare.

Refraction (refraction) of sunlight in the atmosphere is accompanied by their dispersion, i.e. a decomposition into a spectrum. The strength of the refraction depends on the wavelength of the beam: the shorter the wavelength of the beam, the stronger it will rise due to atmospheric refraction.

The result of superposition on each other of the color beams from individual points of the solar disk, the Central part of it will remain white (or rather, due to scattering, the whole disk becomes red) and only the top and bottom edges of the disk are in an advantageous position. Top becoming blue-green, bottom — orange-red. The red and orange part of the disk of the Sun come over the horizon before green and blue.

When the Sun sinks below the horizon, the last light we would see purple. However, the short-wave rays of violet, blue, blue— on a long path in the atmosphere (when the Sun is near the horizon), so strongly scattered that don't reach the earth's surface. In addition, the rays of this part of the spectrum is less than the sensitivity of the human eye.

At extremely high transparency of the air, the last ray can be blue-green and even blue. A similar phenomenon is extremely rare.

It is rarely possible to observe the "red beam". The red beam occurs at the moment of the bottom edge of the disk of the Sun clearly formed under the edge of the clouds covering the rest of the drive. The height of the Sun above the horizon should be minimal, and the air is completely transparent.

Translated by «Yandex.Translator»