Why Is the Sky Blue?

Argument: it is a common sense among people that the sky is blue. Therefore people often use the phrase “blue sky”. In my opinion, the sky (aerosphere) is transparent and the blue sky is the blue inverted reflection of blue seawater that comes into being as the light of blue seawater scatters over the aerosphere after the sun shines on the earth. Aerosphere is a giant transparent spherical concave mirror, which encircles the earth. When the earth’s blue seawater is reflected on the aerosphere, light spreads evenly all over the aerosphere pursuant to the concave mirror (aerosphere) light-scattering principle. As source of reflection, both the earth and aerosphere have a sphere shape. Therefore, the blue light background reflected encircles the entire sky (aerosphere) evenly (as shown in Fig. 1).

Fig. 1

Brief introduction: I have worked in a LED lighting company for a long term, responsible for design and technical jobs. I use integrating sphere (a spherical hollow concave light-scattering sphere) frequently. Therefore I am deeply impressed by the concave mirror (aerosphere) light-scattering principle. In the beginning of 2017, I was sent to go on a business trip by air by my company. As the plane took off, it seemed as if I saw the horizon. After the plane passed through clouds, I saw the blue sky. At that moment, I felt that the aerosphere encircled the earth, just like a giant integrating sphere. That scene was amazing. Then a curious and bold idea came to my mind: is the blue sky caused by the blue sea? Later I thought over the question repeatedly. I searched related information from Internet and bookstores and thought over the common ground and differentia of the argument. Later I drew a conclusion preliminarily that the sky (aerosphere) is transparent and the so-called blue sky is just an inverted image of blue seawater that scatters over the aerosphere. 

1. The blue sky (aerosphere) is a round and transparent gaseous sphere 

With the development of technology, human has reached the space. They have taken pictures of the earth in space. If the sky (aerosphere) is blue, we should be able to see a blue earth from the space. However, we saw blue sea, green forest, yellow desert, and white cloud in fact. 

At night we even can see the light of developed cities in space. Thus we can draw a conclusion that the aerosphere is transparent, the earth is a giant sphere (primary geography textbook knowledge) and its surface is covered by the aerosphere. Based on the same principle, aerosphere should also be a round gaseous sphere (as shown in Figures 2, 3 and 4). 

Fig. 2 

Fig. 3 

Fig. 4 

2. Concave mirror light-scattering principle 

Concave mirror is also called convergent mirror. When parallel rays of light reach a concave mirror, the mirror can scatter and refract light (primary physics textbook knowledge). Its operating principle is similar to that of integrating sphere. When a locally-luminous (reflective) object (e.g. lamp) is put into an integrating sphere, lamplight will scatter all round the sphere evenly. Similarly, when the rays of light reflected by seawater reach a part of aerosphere on the surface of the earth, they are refracted evenly on the entire aerosphere (as source of reflection, the earth is also a round sphere. Therefore rays of light are scattered more evenly). This is the reason why people can see a blue sky (space) on the earth (as shown in Fig. 5). 

Fig. 5: integrating sphere with a light scattering function on the concave surface 

Fig. 6：Schematic diagram of concave mirror astigmatism

3. Seawater is blue. 

The color of seawater saw by people is the color of light of the sun that is reflected by seawater. Sunlight contains seven colors, i.e. red, orange, yellow, green, blue, indigo and violet. These colors have different light wave lengths. From red to violet, light wave length decreases gradually. With a long wave length, red, orange and yellow have a strong penetrating power. Thus they can be absorbed most easily by water molecules. With a short wave length, indigo and violet have a weak penetrating power. They can be scattered and reflected easily under the condition of pure seawater. Moreover, human eyes are insensitive to violet light but sensitive to blue light. Therefore, oceans look blue or dark blue in our eyes. 

(Primary ocean textbook knowledge)

4. There is a very large area of blue oceans on the earth. 

The surface area of the earth is 510 million square kilometers, of which 71% is covered by oceans and 29% covered by land. Wherever the earth rotates, enough blue ocean reflection area is available (as shown in Figures 7, 8 and 9). 

(Primary geography textbook knowledge)

                                                       Fig. 7                                               

Fig. 8 

Fig. 9

Based on the abovementioned four reasons, I draw a conclusion preliminarily that the sky (aerosphere) is transparent and the blue sky is the blue inverted reflection of blue seawater that comes into being as the light of blue seawater scatters over the aerosphere after the sun shines on the earth.

I hope that my view can be accepted by the people in the scientific circles at home and abroad. If you disagree with me, please put forward your standpoints and explanations. Thank you! 

Thesis ---- conclusion! 

The blue sky is a false phenomenon. It is transparent in fact. Upon investigation, it is found that the blue color of the sky derives from blue oceans. When the sun shines on oceans, seawater absorbs sunlight. Then seawater becomes blue. When light of blue seawater is reflected to the sky, the sky becomes blue thoroughly.

--------------------------------------------------------------------------
Name: Hai Long Liu
Telephone: 13249075271
E-mail: 133HFJK90@163.COM