Why Green is Mild for Human?
Though there are some exceptions, most of the plants have green parts including leaves and stems. It is common sense that "green is the mild color for the eyes", but why? In this page, I try to find out the reason.
First of all, let me explain why human recognize colors. Actually, it is not good to use the word "human" here, because even small animals, insects and even bacteria may recognize the colors.
The color of something is generated, because the lights are reflected or absorbed by the thing. For example, red thing looks red because the thing reflects only red light and absorbs other lights, and only the red light reaches to our eyes.
The sunlight includes various kinds of lights, and things look colorful under the sun because they reflect some special colored light and absorb other lights.
The mixture of all kinds of colors look white, and things look black without light, because white things reflect all kinds of lights, and black things absorb all kinds of lights. So called "colorants" are the substances based on this principal.
Now, to thinkg of the difference of the color of the lights, it can be explained as the difference of the wavelength of the lights. The rainbow colors are expressed as red orange yellow green blue dark blue purple, and this order is the order of the wavelength. Red light has the longest wavelength and purple light has the shortest one. When people see these lights, the retina recognizes the difference of the wavelength and informs the brain. That is why we recognizes the color. We do not recognize the color with longer or shorter wavelength, and they are so-called infrared or ultraviolet.
Not only our retina recognize the difference of the wavelength of the light. Plants with bright colors such as red, yellow or purple attract or avoid insects or animals with their color. Of course, insects or animals do not say "how beautiful!", however it is possible to think that the wavelength sends some signals to the insects or the animals in some way.
Let us go back to the subject. Green lights have the wavelength, with which human retina does not feel any difficulty, and human does not require any effort to see green things. So, we do not get tired of seeing green things and keep the concentration. That is why green is often used in the places or occations, where concentration is required. including black boards and baseball fields.
On the other hand, red things make our eyes tired, however they are good to make our nurve excited and make us motivated temporaly.
