Optical phenomena: examples in nature and interesting facts
A person faces light phenomena constantly. Everything connected with the emergence of light, its spread and interaction with matter, is called light phenomena. Vivid examples of optical phenomena can be: rainbow after rain, lightning during a thunderstorm, twinkling stars in the night sky, the play of light in a stream of water, the variability of the ocean and sky, and many others.
Pupils receive a scientific explanation of physical phenomena and optical examples in the 7th grade, when they begin to study physics. For many, optics will be the most fascinating and mysterious section in the school physics program.
What does a person see?
A person's eyes are arranged so that he can perceive only the colors of the rainbow. Today it is already known that the spectrum of the rainbow is not limited to red on the one hand and purple on the other. Behind the red is the infrared color, behind the violet is the ultraviolet.Many animals and insects are able to see these colors, but people, unfortunately, cannot. But on the other hand, a person can create devices that receive and emit light waves of the appropriate length.
Refraction of rays
Visible light is a rainbow of colors, and light of white color, for example, solar, is a simple combination of these colors. If you place a prism into a beam of bright white light, it will break up into colors or waves of different lengths that it consists of. First appears red with a longer wavelength, then orange, yellow, green, blue, and finally purple, which has the shortest wavelength in visible light.
If you take another prism to catch the light of the rainbow and turn it upside down, it will bring all the colors into white. There are many examples of optical phenomena in physics; we will consider some of them.
Why the sky is blue?
Young parents are often confused by the simplest, at first glance, questions of their small social problems. Sometimes the hardest thing to answer them. Virtually all examples of optical phenomena in nature can be explained by modern science.
The sunlight that illuminates the sky during the day is white, which means that theoretically the sky should also be bright white.In order for it to look blue, some processes with light are needed at the moment it passes through the atmosphere of the Earth. This is what happens: some of the light passes through the free space between the gas molecules in the atmosphere, reaching the earth's surface and remaining the same white color as at the beginning of the path. But sunlight hits on gas molecules, which, like oxygen, are absorbed and then scattered in all directions.
Atoms in gas molecules are activated by absorbed light and again emit photons of light in waves of different lengths - from red to purple. Thus, some of the light goes to the earth, the rest goes back to the Sun. The brightness of the emitted light depends on the color. Eight photons of blue light are produced for each photon of red. Therefore, blue light is eight times brighter than red. Intense blue light is emitted from all sides of the billions of gas molecules and reaches our eyes.
People used to think that rainbows are signs that the gods send them. Indeed, beautiful multicolored ribbons always appear in the sky from nowhere, and then disappear in the same way mysteriously.Today we know that rainbow is one of the examples of optical phenomena in physics, but we do not cease to admire it every time we observe it in the sky. It is interesting that each observer sees another rainbow created by rays of light coming from behind him and from the raindrops in front of him.
What are the rainbows?
The recipe for these optical phenomena in nature is simple: water droplets in the air, light and an observer. But it is not enough that the sun appears during the rain. It should be low, and the observer should stand so that the sun was behind him, and look at the place where it is going or just had just rained.
A ray of sunshine overtakes a raindrop. Acting like a prism, a raindrop refracts every color hidden in white light. Thus, when a white ray passes through a raindrop, it suddenly splits into beautiful multicolored rays. Inside the drop, they bump into its inner wall, which acts like a mirror, and the rays are reflected in the same direction from which they penetrated the drop.
As a result, the eyes see a rainbow of colors in the form of an arch across the sky - light bent and reflected by millions of tiny raindrops. They can act like small prisms, splitting white light into a spectrum of colors.But rain is not always necessary to see the rainbow. Light can also be refracted from fog or vapor from the sea.
What color is water?
The answer is obvious - the water is blue. If you pour clean water into a glass, everyone will see its transparency. This is due to the fact that there is too little water in the glass and its color is too pale to see it.
When filling a large glass container, you can see the natural blue shade of water. Its color depends on how water molecules absorb or reflect light. White light is composed of a rainbow of colors, and water molecules absorb most of the colors of the spectrum from red to green, which passes through them. And the blue part is reflected back. So we see the blue color.
Sunrises and sunsets
These are also examples of optical phenomena that a person observes every day. When the sun rises and sets, it directs its rays at an angle to the place where the observer is located. They have a longer journey than when the sun is at its zenith.
Layers of air above the Earth’s surface often contain a lot of dust or microscopic particles of moisture. The sun's rays pass at an angle to the surface and are filtered.Red rays have the longest wave of radiation and therefore make their way easier to the ground than blue ones with short waves that are bounced off with particles of dust and water. Therefore, during the morning and evening dawn, a person observes only a portion of the sun’s rays that reach the earth, namely the red ones.
Light show planet
A typical aurora is a colorful glow in the night sky that can be seen every night at the North Pole. The huge stripes of blue-green light, with orange and red spots changing in bizarre forms, sometimes reach over 160 km wide and can extend up to 1600 km long.
How to explain this optical phenomenon, which is such a spectacular sight? Shines appear on Earth, but they are caused by processes occurring in the distant Sun.
How is everything going?
The sun is a huge gas ball, consisting mainly of hydrogen and helium atoms. All of them have protons with a positive charge and electrons rotating around them with a negative charge. Constantly a halo of hot gas spreads into space in the form of solar wind.This countless protons and electrons rushing at a speed of 1000 km per second.
When the particles of the solar wind reach the Earth, they are attracted by the strong magnetic field of the planet. Earth is a giant magnet with magnetic lines that converge at the North and South Poles. The attracted particles are located along these invisible lines not far from the poles and collide with the nitrogen and oxygen atoms that make up the Earth’s atmosphere.
Some of the earth's atoms lose their electrons, others are charged with new energy. After a collision with the protons and electrons of the Sun, they give off photons of light. For example, nitrogen that has lost electrons attracts violet and blue light, and charged nitrogen shines with a dark red light. The charged oxygen gives off green and red light. Thus, the charged particles cause the air to overflow with many colors. This is the aurora.
One should immediately determine that mirages are not the fruit of human imagination, they can even be photographed, they are almost mystical examples of optical physical phenomena.
There are many evidences of observing mirages, but science can provide a scientific explanation for this miracle. They can be simple, such as a piece of water among hot sands, and they can be incredibly complex by constructing visions of hanging castles with columns or frigates. All these examples of optical phenomena are created by the play of light and air.
Light waves are bent when they first pass through warm, then cold air. Hot air is more rarefied than cold, so its molecules are more active and diverge to farther distances. With a decrease in temperature, the movement of molecules also decreases.
Visions observed through the lenses of the earth's atmosphere can be greatly modified, compressed, extended, or inverted. This is because the rays of light bend, passing through the warm and then cold air, and vice versa. And those images that carry a luminous flux, such as the sky, can affect the hot sand and seem like a piece of water, which always moves away when approaching.
Most often, mirages can be observed at large distances: in deserts, seas and oceans, where hot and cold layers of air with different densities can be located at the same time.It is the passage through different temperature layers that is able to twist the light wave and get a vision as a result, which is a reflection of something and presented by fantasy as a real phenomenon.
For most optical illusions that can be observed with the naked eye, the explanation is the refraction of sunlight in the atmosphere. One of the most unusual examples of optical phenomena is the solar halo. In fact, halo is a rainbow around the sun. However, it differs from the usual rainbow both in appearance and in its properties.
This phenomenon has many varieties, each of which is beautiful in its own way. But for the emergence of any kind of optical illusion, certain conditions are necessary.
Halo occurs in the sky when several factors coincide. Most often it can be seen in frosty weather with high humidity. There is a large amount of ice crystals in the air. Breaking through them, the sunlight is refracted in such a way that it forms an arc around the sun.
And although the last 3 examples of optical phenomena are easily explained by modern science, for an ordinary observer, they often remain a mystery and a mystery.
Having considered the main examples of optical phenomena, it is safe to believe that many of them are explained by modern science, despite its mystery and mysteriousness. But scientists still have a lot of discoveries ahead, clues of mysterious phenomena that occur on planet Earth and beyond.