The phenomenon of the sky appearing orange and red at sunrise and sunset is primarily due to the scattering of sunlight by Earth's atmosphere. To understand this, let's explore the science behind it.
During sunrise and sunset, the sun is positioned lower in the sky, and its light has to pass through a larger portion of the Earth's atmosphere before reaching our eyes. The Earth's atmosphere is composed of various gases, as well as tiny particles such as dust, water droplets, and pollutants.
When sunlight passes through the atmosphere, it encounters molecules and particles that scatter the light. The Earth's atmosphere scatters shorter wavelengths of light, such as blue and violet, more than longer wavelengths like red and orange. This phenomenon is known as Rayleigh scattering.
During midday, when the sun is high in the sky, the shorter blue and violet wavelengths are scattered in all directions, making the sky appear blue to our eyes. However, during sunrise and sunset, the sunlight has to traverse a greater distance through the atmosphere, and most of the shorter blue and violet wavelengths get scattered away from our line of sight.
As a result, the longer wavelengths, particularly red and orange, tend to dominate the scattered light that reaches our eyes. This gives rise to the warm hues of orange and red that we see during sunrise and sunset. The light passes through a larger slice of the atmosphere, and more scattering occurs, resulting in the vibrant colors often associated with these times of the day.
Furthermore, the atmosphere can also contain additional particles, such as dust or pollution, which can contribute to the scattering and enhance the redness or intensity of the colors observed during sunrise and sunset. These particles can scatter a broader range of wavelengths, including some of the longer red and orange wavelengths, making the colors even more pronounced.
In summary, the orange and red colors observed at sunrise and sunset are a result of the scattering of shorter wavelengths of light and the longer wavelengths, particularly red and orange, dominating the scattered light that reaches our eyes due to the Earth's atmosphere.