Man is a great master at building castles in the sand. However, practice shows: he is far from mother of nature. A mistress from God is capable of such a deception of our feelings that it is breathtaking! But no matter how magical the optical phenomena look, examples of which we will consider, they are not phantasmagoria, but the result of the course of physical processes. In the heterogeneous atmosphere of the Earth, the rays of light bend, causing a host of illusions. But is it possible to imagine a world without dreams and visions? He would be so gray ...
Light and color
Speaking about optical phenomena, the light and forms of which are observed by more than one generation of people, we emphasize that colors appear in the atmosphere due to the fact that white light in the course of interaction with materials in the atmosphere is divided into its constituent parts (spectrum). This interaction is carried out using one of three main forms: reflection, refraction (refraction) and diffraction.
If we are talking about the spectrum, think about how to teach your child to remember the totality of the color bands obtained when a light beam passes through a refractive medium. A simple phrase will help: "Each (red) hunter (orange) wants (yellow) to know (green), where (blue) sits (blue) pheasant (purple)."
Reflection of light is the occurrence of secondary waves propagating from the boundary of two media back to the first medium. Refraction is the refraction of rays at the boundary of two media. Diffraction - bending by light streams of solid particles, liquid droplets, as well as other materials present in the atmosphere. All this is the reason for the "optical optical illusion" that flourishes in the Universe. There are many examples: from the blue of the sky, mirages and rainbows to false suns and solar pillars.
Internal reflection
Optical phenomena in physics is an important section worthy of deep study. So let's continue. Reflection occurs when light rays fall on a smooth surface and return at an angle equal to the incoming. This phenomenon explains the origin of color: some parts of white are more easily absorbed and reflected than others. For example, an object that appears to be green appears to be so because it absorbs all wavelengths of white light, with the exception of green, which is reflected.
One form - internal reflection - is often present in the explanation of optical phenomena. Light enters a transparent physical body (material), for example, a drop of water, through the outer surface and reflects already from the inside. Then, the second time - from the material. The color of the rainbow can be partially explained in terms of internal reflection.
Rainbow arc
A rainbow is an optical phenomenon that occurs when sunlight and rain combine in a specific way. The rays of sunlight are divided into the colors that we see in the rainbow when they enter the raindrops. This happens when the beam hits the "rain" directed to the Earth at a certain angle, the colors separate (white light decomposes into a spectrum), and we see a bright, festive rainbow that resembles a giant semicircular bridge.
Variegation of curved stripes seems to hang directly above your head. The radiating source will always be behind us: you cannot see the clear sun and the beauty-rainbow right away (unless, if you use a mirror for this purpose). The phenomenon is not alien to the moon. When the moonlit night is bright, you can see a rainbow "fan" in the vicinity of Selena.
When almost nothing is visible around, the most receptive to light photoreceptors of the human eye - “sticks”. They are sensitive to the emerald-green part of the spectrum, they do not see other colors. As a result, the rainbow looks whitish. When the lighting is amplified, “cones” are connected, thanks to these nerve endings the arc looks more colorful.
Mirage
From Earth, we observe only part of the circumference of the primary rainbow. The light undergoes one reflection. In the mountains you can see a round rainbow. Do you know that there are two or even three “beauties”? A rainbow tossed over a rainbow, less bright and “inverted” (after all, this is a reflection of the first). The third happens where the air is crystal clear and transparent (for example, in the mountains). This is for a familiar sight.
A mirage is an optical phenomenon that cannot be called ordinary. In Russia, it is relatively rare. Each time we utter a magic word, we recall the legend of the ghost ship Flying Dutchman. According to the legends, for the captain’s crimes he will plow the ocean open spaces until the second coming.
And here is another "Dutchman." The Ripals cruiser, which sank in December 1941 off the coast of Ceylon, became flying. He was seen "very close" by the crew of the British ship Vendor, located in the area of the Maldives. In fact, the ships shared 900 kilometers!
Fata Morgana
The Flying Dutchman and others are optical phenomena, examples from a cohort of stunning mirages of “Fata Morgana” (named after the heroine of the British epic). An unusual optical phenomenon is a combination of several forms at once. A complex, rapidly changing image forms in the sky. Looking at the views of what is far beyond the horizon, it seems you can go crazy, they are so "tangible".
Miracles caused by atmospheric conditions can confuse anyone. Especially such as the appearance of a "layer of water" in the desert or on a hot road, caused by the refraction of rays. Not only children, but also adults cannot escape the feeling that animals, wells, trees, buildings are real. But alas!
Light passes through layers of unevenly heated air, creating a peculiar 3D image. Mirages are lower (a distant, flat surface takes the form of open water), side mirages (occur next to a very hot vertical surface), chrono (reproduce past events).
Northern Lights
Reflecting on what optical phenomena are, it is impossible not to say about the northern (polar) lights. It has two main forms: beautiful sparkling ribbons and spots resembling clouds. Intense shine, as a rule, "tape". It happens that colored luminous stripes cease to exist without breaking into components.
In the darkness of celestial space, the curtain, as a rule, stretches from east to west. A “train” can reach several thousand kilometers in width, and several hundred in height. This is not dense, but a thin "screen" through which the stars sparkle. A very beautiful sight.
The lower edge of the "wings" is clear, has a reddish or pink tint, the upper one seems to dissolve in the dark, due to which the inexpressible depth of space is well felt. We discuss four types of auroras.
Homogeneous structure
A calm, simple form of radiance, bright from below and dissolving above, is called a homogeneous arc; active, mobile, with small folds and trickles - a radiant arc. Shining folds superimposed on each other (large to small) are called the "radiant strip."
And the fourth view is when the area of folds and loops becomes very large. After the activity ends, the tape acquires a homogeneous structure. It is believed that homogeneity is the main property of "His Excellency." Folds occur only during periods of increased atmospheric activity.
There are other optical phenomena. Examples are not slow to list below. A flurry is a radiance that gives the entire polar cap a whitish-green glow. It is observed at the southern and northern poles of the Earth, in Iceland, Norway, etc. The phenomenon arises as a result of the glow of the magnetized upper layers of the atmosphere when interacting with charged particles of the solar wind (as the so-called outflow into space of plasma from helium and hydrogen).
About light poles, one can say the following: they are frequent on frosty days, very spectacular.
Saint Elm in the crowns of green rays and halo
There are other optical phenomena. For example, a halo whose appearance is associated with ice crystals formed in the atmosphere. It is related to a rainbow by dispersion (decomposition of light into components), only not in a drop, but in the solid structure of ice.
Rainbows are similar to each other, because the drops are the same, they can only fall. The halo has a hundred species, as the crystals are different and very “nimble”: they hover, now they swirl, then they rush to the Earth.
Dreaming once again to "be deceived", you can admire the false sun (pargelium) or the lights of St. Elmo. The latter "sit" on the masts of ships, sharp peaks of tall buildings. Mystery has nothing to do with it. This is an electrical discharge in the atmosphere. It often occurs during a thunderstorm or in a sandstorm (when particles are electrified).
Photographers like to catch the "green ray" (a flash over the sun and the refraction of rays near the horizon). It is best to capture it in open spaces, in cloudless weather. But the crowns (light diffraction) are clearly visible when the area is covered with fog (the rainbow circles around the headlights of your car - this is the crowns), and the sky is obscured by a veil of clouds. In a fog of small droplets, circles are especially beautiful. When the fog thickens, they blur. Therefore, a decrease in the number of rainbow rings is regarded as a signal of worsening weather. What a huge world this is - optical phenomena! The examples we have analyzed are just the tip of the iceberg. Knowing about these phenomena, we can scientifically explain any atmospheric illusion.