It is almost second to nature to ask questions about one’s environment as one grows up from childhood to adulthood. Some aspects of the environment are very mysterious and appear as magical when view through a lay man’s eyes. However, hope has been brought through scientific studies and experiments. For instance, as I was growing up, I always wondered why the sky is blue. Does this mean that outer space is also blue? Or is it just a reflection of the oceans’ color? These and many other questions lingered in my head for years until I first entered a science class and realized that there is more to the blue light than just color.
There are several opinions on why the sky appears to be blue. Some people believe it is the reflection of the oceans’ color while others believe it is the reflection of the blue portion of the light from the sun that is reflected on the surface of dust particles in the atmosphere. Others believe that both the sky and the oceans are intrinsically blue. The truth is, in fact, that all these opinions are just misconceptions. They can be easily disapproved.
For example, if the sky and ocean water were inherently blue, why does the water look transparent? Why does the sky appear grey? These questions simply disapprove that argument. This was one of the phenomena I wanted to understand from the science class. As I came to realize, science addresses all my concerns when it comes to the sky’s color. Some of these explanations will dominate this document in the endeavor of finding out the most rational, relevant and realistic explanation to the blue color of the sky.
The explanation starts by understanding the inevitability of solar radiation to the life on the Earth. The light and energy from the sun dictates a lot of things on earth like the type of vegetation, the climate of an area and resources available in different areas (Hoeppe 5).
On top of all that, the sun also affects the appearance of the sky in different parts of the day. A summary of the whole phenomenon makes it simpler and easier to comprehend. Initially, the light from the sun travels in small ‘packets’ of light called photons (Hoeppe 5).
Photons are particulate in nature, similar to atoms. As the light travels through space into the earth’s atmosphere, it collides with the numerous molecules in the atmosphere. The light from the sun appears white in color since it is a combination of several wavelengths of light. The consolidating of all these colors of the spectrum leads to a white light. Just as a prism splits white light into the colors of the spectrum, the atmospheric molecules split the light from the sun into the various constituents of the white light. The spectrum is not entirely visible to the naked human eye. In fact, human beings can only see the parts between the red and violet.
These fall between the wavelengths of 380 nanometers (violet) and 720 nanometers (red). Between red and violet fall orange then yellow then green and finally blue. The blue portion of this white light is made up of very light particles that have very small wavelengths (Hoeppe 5). Therefore, when the white light travels through air and collides with the particles in it, it is scattered more than the others. Thus, the sky appears blue in color.
The scattering of the light is less at night. This is because there are minimal atmospheric movements at night in the upper parts of the atmosphere since temperatures are low. High temperatures during the day result to expansion of gases hence they become lighter and rise. The risen air causes the scattering of the white light to produce the blue appearance of the sky. The reverse happens at night hence light travels in an almost linear path hence there little scattering and/or absorption of light in the atmosphere. This simple explanation is the blue print of the wider and more technical explanation. The earth’s atmosphere is majorly composed of nitrogen (78 percent) and oxygen (21%).
The diameter of the earth’s atmosphere (the diameter of the nitrogen and oxygen molecules) is such that it effectively splits light with wavelengths around the blue and blue-like colors (Hoeppe 5). Orange, red and other parts of the spectrum falling under this bracket of wavelength pierce through the particles of the air undistorted. The sky, therefore, appears blue since it is only the blue portion of the white light that is scattered by the oxygen molecules.
Even though the blue light is the one that is scattered most, the atmospheric particles also distort the violet portion of the light. Why then does the sky appear blue and not as an agglomeration of blue and violet. This observation can be blamed on the nature of the natural naked human eye. The human eye is particularly sensitive to blue, green and red. Since the scattered light is a combination of blue and violet, and the human light is more sensitive to the blue light, the biased appearance of the sky will be automatically blue.
Moreover, the sun does not discharge light of different wavelengths with the same intensity. The violet light is particularly discharged in lower intensities compared to the blue light. Moreover, the wavelength of the violet light allows it to be absorbed by the particles in the upper sections of the earth’s atmosphere. Thus, very minimal violet light strikes the human eye on the surface of the earth.
The color of the sun is therefore a speculation. Its appearance is a product of several processes that include scattering of white light, selection of the wavelengths by the human eye and absorption of violet light in the upper atmosphere.
Works Cited
Hoeppe, Götz. Why the Sky Is Blue: Discovering the Color of Life. Princeton, N.J: Princeton University, 2007. Print.