Green Flash is a sunset phenomenon, but can also occur weakly at sunrise. It is a green spot which is seen briefly within a blink of an eye, above the top of the sun peeks above the horizon. The green flash or rays occurs due to the dispersion of sunlight with the atmosphere acting as a weak prism.
Green flashes are observed from any altitude such as top of a mountain. It can also be observed from the horizon, such as over the ocean, but are possible over cloud tops. It is called flashes because it occurs for a very short period of time, let's say about one to two seconds. This flashes are specifically observed by air pilots, particularly when flying westwards when there is a slow sunset.
green flashes are triggered by mirage which increases refraction. The green flash is viewable because refraction bends the light of the sun.
Air can act just like a prism to spread sunlight into its component colors. The degree to which light beams refract depends on their color (wavelength). Refraction is strongest when the Sun lies low above the horizon, creating a blue-green fringe on the top edge of its disk.
Night Sky
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When the sun's disk is fully visible above the horizon, the different colors of light rays overlap to an extent where each individual color can't be seen by the naked eye. When the sun starts to dip below the horizon the colors of the spectrum disappear one at a time, starting with those with the longest wavelengths to those with the shortest. That's why you mostly see red light during sunset because it has the longest wavelength and therefore the leading in the visible spectrum (ROYGIV)
- R - Red (longest wavelength)
- O - Orange
- Y - Yellow
- G - Green
- I - Indigo
- V - Violet (shortest wavelength)
That's why when you look closely during sunset, there is a transformation of the red light partial visible orange to partial visible yellow. The green light might be a little hard to see with naked eye. Sometimes, when the air is especially clear, enough the blue or violet light rays make it through the atmosphere, causing a blue flash to be visible.
Green flashes fall into two categories: inferior mirage flashes and mock mirage flashes
**One popular but inaccurate explanation attributes green flashes to the sun shining through the waves on the ocean. However, the light entering a wave is bent downward, into the water and cannot escape.**
Green light is a beautiful natural phenomenon which every one will like to observe. But, the only problem is it cannot be seen on a ground level. It can only be observed through the horizon.
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