Every one of us has witnessed sunrise and sunset several times. But have you ever noticed that many times, the sky appears to be green during sunrise or sunset? Sometimes this phenomenon can be seen after sunrise or just before that sunrise. But what is the reason behind this change of colour?
In an interview with Live Science, Johannes Courtial, a scientist at the University of Glasgow explained that the light of the sun is usually white. However, when the white light passes through a medium with a higher density, such as glass or water at a certain angle, the wavelengths get separated and as a result, we get to see lights of different colours. Scientifically the phenomenon is known as refraction of light. Let us first know how the different colours of the rainbow appear.
Earth’s atmosphere consists of various gases with different densities which is one of the main reasons behind the refraction of light. This is the phenomenon why we get to see rainbows even when there is no rain. Refraction of lights is particularly noticeable when the sun is very close to the horizon. This mainly happens during sunrise and sunset. As the sunlight enters the dense part of the earth’s atmosphere at a certain angle we get to see a greenish flash appear on the sky.
Why this phenomenon takes place?
The question arises, why the light that appears is specifically green in colour? We all know that the colour green is a mixture of two colours blue and yellow. During sunrise and sunset when the sunlight falls at a specific angle, the wavelength of the blue light and the yellow light overlap with each other producing a greenish phenomenon. This phenomenon is mainly visible in coastal areas and mountains. This is mostly witnessed in Coastal areas when the warm air creates a blanket over the cold water. The air layers refract the sunlight which leads to this phenomenon.
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