RAINBOW AND ITS BEAUTY
A rainbow is an optical and meteorological phenomenon that consists in the appearance in the sky of an arc (sometimes, two) of multicolored light, caused by the decomposition of sunlight in the visible spectrum, which is produced by refraction, when the sun's rays pass through small drops of water contained in the Earth's atmosphere. It is a bow composed of concentric arcs of colors, with no solution of continuity between them, with red towards the outside and violet towards the inside.
DECOMPOSITION OF THE LIGHT IN A DROP OF WATER.
Respect to the conditions to see a rainbow are reduced to that the observer has to be located between the sun and a rain of spherical drops (a uniform rain). It is possible that the observer believes that the rain is not uniform where he is, but it must be from where he would locate the rainbow. And when are the spherical drops? The drops are spherical when they fall at a uniform, constant speed. This is possible in conditions of gravitational acceleration counting on the viscous opposing forces of the air. When it is satisfied that the speed of the drops is uniform, the drop acquires a maximum volume with the minimum surface (sphere). Only in these conditions is possible the light scattering within the drop and therefore the rainbow, although slight variations of the sphere can give various variations in a rainbow. Therefore, the rain should not be torrential, nor be affected by the wind. That is why the rainbow is not always contemplated when there is rain and sun.
It is important to note the height of the Sun when one observes a rainbow, because it helps determine how much one can see of it: the lower the Sun is, the higher the rainbow crest and vice versa. Someone who can rise a little above the surface of the Earth, would realize that certain arcs continue below the horizon. Those who climb high mountains have sometimes seen a good part of complete circular arcs. But even the mountains are not high enough to be able to see a circular rainbow in its entirety.
HISTORY
More than three centuries ago, Isaac Newton managed to demonstrate with the help of a prism that the white light of the Sun contains colors starting from red, in turn going through orange, yellow, through green, through blue and indigo until it reaches violet . This separation of light in the colors that make it is called the decomposition of white light.
Newton's experiment is not difficult to reproduce, since it is not necessary to have special scientific instruments to carry it out. Even today it turns out to be one of the most beautiful and instructive for the incipient students of optics in basic, middle and higher education. It can be achieved with a prism, which, when traversed by a beam of white light from the sun, causes the ray of sunlight to refract and exit from the opposite side decomposed in the 7 colors already mentioned.
But many centuries before Newton was born nature had already decomposed the sunlight again and again before the eyes of our ancestors. Sometimes, after a drizzle; others, after a storm. The truth is that the rainbow was for a long time a phenomenon as amazing as overwhelming. Sometimes taken as a carrier of auguries, in others as the inspiration of a legend, and always as a work of art, the human being has never ceased to seem wonderful.
After the flood God told Noah that the rainbow would serve as a sign to remember that there will be no more flood of waters to destroy all flesh (Genesis 9: 9-17)
And God said: This is the sign of the covenant that I establish between me and you and every living creature that is with you, for everlasting centuries: My bow I have set in the clouds, which will be a sign of the covenant between me and the earth. And it will happen that when I bring clouds over the earth, my bow will be seen in the clouds. And I will remember my covenant, which is between me and you and every living creature of all flesh; and there will be no more flood of waters to destroy all flesh.
According to Exekiel, as the rainbow seems to be in the clouds on the day it rains, so will the appearance of the radiance ... of the likeness of the glory of the Lord (Ezekiel 1:28), and I saw an appearance like shining bronze, like an appearance of a fire inside her around her, from the side of her hips upwards; and from his hips down, I saw that it looked like fire and that it had a glow around it. Like the appearance of the rainbow that is in the clouds in the rainy day, so was the appearance of the brightness around.
John saw around the throne a rainbow and an angel with the rainbow on his head (Revelation 4: 3, 10: 1). The appearance of which he was sitting was similar to a jasper and carnelian stone, and around the throne there was a rainbow similar in appearance to the emerald .... I saw another strong angel come down from heaven, wrapped in a cloud, with the rainbow on his head. His face was like the sun and his feet like pillars of fire.
We human beings marvel at the greatness of the works of God and all the things she put into the natural and we should take care of it as much as possible since we live in it, and God placed us here to live our lives together....