What natural phenomenon will happen when the sun shines after rain and snow? Please give an example and describe its shape.

1. Rainbow, also known as the rainbow, is called rainbow for short, and "color", as the name implies, means "colorful" and "colorful". "Rainbow" and "Gong" represent phonetics, while "Bug" represents form. Why is it next to the word "worm"? Because in ancient times, people didn't know that raindrops were related to raindrops, and thought raindrops were insects that drank raindrops, so the word "insects" was used.

Rainbow is an optical phenomenon in meteorology. When sunlight hits the raindrops in mid-air, the light is refracted and reflected, forming an arched color spectrum in the sky. The colorful colors of the rainbow are red, orange, yellow, green, blue, indigo and purple from outside to inside.

Rainbow is a natural phenomenon, which is caused by the reflection and refraction of sunlight when it hits water droplets in the air.

Rainbow [natural phenomenon]

cause

Optical principle chart of rainbow formation

Rainbow is formed by the scattering and reflection of sunlight on small round water droplets in the air. When sunlight enters the water drop, it will be incident at different angles at the same time and reflected at different angles in the water drop. The reflection of 40 to 42 degrees is the strongest, which produces the rainbow we see. When this reflection occurs, sunlight enters the water drop, refracts once, then reflects on the back of the water drop, and finally refracts again when it leaves the water drop. Because water has a dispersive effect on light, the refractive index of light with different wavelengths is different, and the refractive angle of blue light is greater than that of red light. Because light is reflected in water droplets, the spectrum seen by the observer is reversed, with red light at the top and other colors at the bottom.

In fact, as long as there are water droplets in the air and the sun shines behind the observer at a low angle, an observable rainbow phenomenon may occur. Rainbow usually appears in the afternoon, when the rain clears. At this time, the air is less dusty and full of water droplets, and one side of the sky is dark because of rain clouds. However, observers can see the sunlight without being covered by clouds above or behind them, so rainbows are easier to see. Another place where rainbows are often seen is near waterfalls. When the weather is clear, you can spray water or mist into the air with your back to the sun, or you can make rainbows artificially.

Rainbow [natural phenomenon]

Appearing position

The rainbow does not actually appear in a specific position in mid-air. It is an optical phenomenon seen by the observer, and the position of the rainbow will change with the observer. When an observer sees a rainbow, its position must be in the opposite direction of the sun. The center inside the rainbow arch is actually an enlarged image of the sun reflected by water droplets. So the sky inside the rainbow is brighter than the sky outside the rainbow. The center of the rainbow arch is just the direction of the observer's head shadow, and the rainbow itself is 40 to 42 degrees above the line between the observer's head shadow and his eyes. Therefore, when the sun is higher than 42 degrees in the sky, the rainbow will be below the horizon and invisible. This is why rainbows rarely appear at noon.

Rainbow [natural phenomenon]

shape

The rainbow extends from one end to the other. With an ordinary 35mm camera, you need a wide-angle lens with a focal length below 19mm to capture the whole rainbow in a single frame. If you are on an airplane, you will see that the rainbow is round rather than arched, and the center of the circular rainbow is the direction of the airplane.

Sunset is a rare phenomenon, which may appear in the night with strong moonlight. Because it is difficult for human vision to distinguish colors in low light at night, the night rainbow looks as if it is all white.

Rainbow [natural phenomenon]

colour

The size of water droplets in the air determines the bright color and width of the rainbow. When the water drops in the air are large, the rainbow is bright and narrow; On the contrary, if the water drops are small, the rainbow will be light and wide. We can't see the rainbow in front of the sun, but only in front of the sun, so the rainbow appears in the west in the morning and always in the east at night. But we can't see it. We can only see it from the sky by plane. The appearance of rainbow is related to the weather change at that time. Generally, we can infer whether it was sunny or rainy from the position where the rainbow appeared in the sky. When there is a rainbow in the east, it is not easy to rain locally, but when there is a rainbow in the west, it is likely to rain locally.

The visibility of rainbow depends on the size of water droplets in the air. The bigger the water drop, the brighter the rainbow, and the smaller the water drop, the less obvious the rainbow is. Generally, in winter, the temperature is low, there are few water droplets in the air, and there are few opportunities for showers, so rainbows generally do not appear in winter.

A rare rainbow formed by moonlight

This rare ghost photo shows the colorful rainbow at night. This rainbow was produced by moonlight, and was photographed by a camera in North Yorkshire.

On June 6, 2009,165438+1October 6, 2009, this rare ghost picture shows a complete moon rainbow, which spans the whole Richmond village in North Yorkshire. We know that when sunlight is reflected by raindrops, rainbows will appear. However, in this case, the sun has set. On the contrary, this impressive arc was created by a special bright moon.

Photographer Chris

Walker captured this moment and filmed it. It was around 7 pm on Sunday, and he was driving through a storm.

He said, "When I drove home, I found something strange in the sky. When the moon was about to become a full moon, it was behind me. At this time, a strong wind blew and the rain poured from the clouds to the horizon in an instant. The moon is so bright that it is obvious that the object in the sky is a rainbow, which is illuminated by moonlight at this time. " "Because moonlight is thousands of times weaker than sunlight, this moonlight rainbow is also much weaker than the sun rainbow, which can only be seen when the moon is close to the full moon. Although the moon rainbow is white to people, you can capture its color when you use the long exposure of the camera. "

In this case, Mr. Walker can reveal all the colors of the moonlight rainbow with only 30 seconds exposure time on his Lumix digital camera. Mr. Walker said, "The moonlight is so bright that I can't see the red in the moonlight rainbow with my naked eyes."

This moonlight rainbow always appears in the opposite part of the sky, opposite to the moon, and is most easily seen only when the moon is close to the full moon. They generally appear less, because the appearance of moonlight rainbow needs the assistance of many conditions. The angle of the moon in the sky must be less than 42 degrees, and the sky must be very dark. And it must be raining in the sky opposite the moon. Moreover, the moon rainbow is more likely to appear next to the waterfall. This phenomenon should not be confused with lunar halo. The halo of the moon appears around the moon and looks like a ring. These moon rings are formed by the refraction of crystals suspended in the upper atmosphere when moonlight passes through the upper atmosphere.

Rainbow [natural phenomenon]

Double rainbow

Double rainbow: the outer ring is neon and the inner ring is rainbow atlas.

Many times, two rainbows will appear at the same time, and a concentric but darker secondary rainbow (also called neon) will appear outside the ordinary rainbow. The secondary rainbow is formed by two reflections of sunlight in water droplets. When sunlight passes through water droplets, it will be refracted, reflected and then refracted again. Our common rainbow (main rainbow) is formed by the reflection of light in water droplets. If light is reflected twice in a water drop, a second rainbow (neon) will be produced. The color arrangement of neon is opposite to that of the main rainbow. Because every reflection will lose some light energy, the brightness of neon lights is also very weak. The strongest reflection angle of the two reflections occurs at 50 to 53, so the position of the secondary rainbow is outside the main rainbow. Because there are two reflections, the color sequence of the auxiliary rainbow is opposite to that of the main rainbow, with the outer side being blue and the inner side being red. In fact, the auxiliary rainbow must follow the main rainbow, but sometimes it is invisible to the naked eye because of the low light intensity. Double rainbow over Scotland 1307, it was suggested in Europe that the rainbow was caused by the refraction and reflection of the sun light by water droplets. Descartes found in 1637 that the size of water droplets does not affect the refraction of light. He experimented by injecting water into the glass ball and got the refractive index of water to light. He mathematically proved that the main rainbow is caused by reflection at the water point, while the auxiliary rainbow is caused by two reflections. He calculated the angle of the rainbow accurately, but failed to explain its colorful colors. Later, Newton discovered all the optical principles of rainbow formation after scattering sunlight into color with a glass rhombus.

Rainbow [natural phenomenon]

Bending principle

One reason: the wavelength of light determines the degree of bending of light.

Rainbow is an atlas of optical phenomena.

In fact, if the conditions are right, you can see a full circle of circular rainbows. The water droplets emitted by sunlight into the air are refracted → reflected → refracted, and then emitted to our eyes, forming a rainbow. The deflection angle between the rainbow beam formed by different colors of solar beams and the original beam is about 180-42= 138 degrees. That is to say, if the sunlight is horizontal to the ground, the elevation angle of viewing the rainbow is about 42 degrees.

Imagine you are looking at the rainbow in the east, and the sun is setting in the west behind you. White sunlight (the combination of all colors in the rainbow) passes through the atmosphere, passes eastward over your head, and meets the water drops falling in the storm. When the light beam touches the water drop, there are two possibilities: first, the light may directly penetrate it, or more interestingly, it may touch the front edge of the water drop, bend the inside of the water drop when it enters, then reflect back from the back end of the water drop, and then leave from the front end of the water drop and refract it to us. This is the light that forms a rainbow.

The bending degree of light passing through water drops depends on the wavelength (i.e. color) of light-red light has the largest bending degree, followed by orange light and yellow light, and so on, and violet light has the smallest bending degree. 1 Each color has its own specific bending angle. The refraction angle of red light in sunlight is 42 degrees, and the refraction angle of blue light is only 40 degrees, so each color appears in a different position in the sky.

If an imaginary line is used to connect the back of the head with the sun, then the place at an angle of 42 degrees with this line is where the red color is. These different positions outline an arc. Since the angle between the blue and the imaginary line is only 40 degrees, the blue arc on the rainbow is always below the red.

The reason why the rainbow is curved is, of course, inseparable from its formation and has a lot to do with the shape of the earth. Because the earth's surface is curved and covered by a thick atmosphere, the water content in the air after rain is higher than usual. When sunlight shines into the air, water droplets will be refracted. At the same time, because the atmosphere on the surface of the earth is curved, the sunlight refracts on the surface to form the arc rainbow we see!

Reason 2: It has a lot to do with the shape of the earth.

Because the earth's surface is a curved surface and is covered by a thick atmosphere, the water content in the air after rain is higher than usual, and the sunlight is refracted when it turns into small water droplets in the air. At the same time, because the atmosphere on the earth's surface is curved, sunlight refracts on the surface, forming the arc rainbow we see!

Rainbow [natural phenomenon]

Mythical religion

myth

Rainbow occupies a place in myth because of its beautiful and incomprehensible phenomena. Galileo's monograph on the characteristics of light can only explain the rainbow phenomenon.

In China mythology, Nu Wa tried to make up the sky with five-color stones, and the rainbow was the colored light emitted by the five-color stones.

In Greek mythology, the rainbow (Iris) is the messenger of communication between heaven and earth.

In Irish mythology, rich goblins put their treasures at the end of the rainbow.

In Indian mythology, the rainbow is the bow of Indra (also translated as Indra) and is called Indra. ..

In Norse mythology, the Rainbow Bridge (Bifr? St) Connect the realm of God "Asgard”(Asg? Rd) and the human settlement "Middle Earth" (Midg? rd)。

Among Taroko people in Taiwan Province Province, the end of the rainbow is the location of the ancestral soul.

religion

In the Hebrew part of the Jewish and Christian classics, Genesis records that God told Noah to build an ark to destroy the world. After that, he made a Covenant with Noah and his descendants with a rainbow, and never again sent a big flood to destroy the world. This is the significance of explaining the rainbow phenomenon on the earth with historical information.

2. Blue sky and white clouds

Clouds are the tangible result of the huge water cycle on the earth. The sun shines on the surface of the earth, and water evaporates to form water vapor. Once the water vapor is supersaturated, water molecules will gather around the dust (condensation nucleus) in the air, and the generated water droplets or ice crystals will scatter sunlight in all directions, thus creating the appearance of clouds. Because clouds reflect and scatter electromagnetic waves in all bands, their colors are gray, and when they are thin, they are white, but when they become too thick or dense for sunlight to pass through, they may look gray or black.

There are clouds on planets other than the earth, but water is not necessarily the main component of clouds on other planets, such as the sulfuric acid cloud of Venus.

Genesis analysis editor

The water on the ground absorbs heat and turns into steam, which rises to the upper layer of the steam layer in the sky. Due to the lower temperature of the upper steam layer, the steam volume decreases, the specific gravity increases and the steam decreases. Because the temperature below the steam layer is relatively high, it absorbs heat in the process of falling, rises and then falls when it is cold, so the gas molecules gradually contract and finally concentrate at the bottom of the steam layer. A low temperature zone is formed at the bottom, and water vapor is concentrated in the low temperature zone, forming a cloud.

3. the sun

The sun is a huge and hot gas planet. Know the distance between the sun and the earth, and then

The viewing angle diameter of the sun's circular surface is measured from the earth. From the simple triangular relationship, the radius of the sun can be found to be 696,000 kilometers, which is 109 times that of radius of the earth. From this, it can be calculated that the volume of the sun is 6.5438+0.3 million times that of the earth.

According to Kepler's third law of planetary motion, astronomers can also calculate that the mass of the sun is 1.989× 10 30 kg, which is 330,000 times that of the earth. And concentrated 99.86% of the mass of the solar system. However, even such a behemoth, in the vast universe, is only an ordinary star of medium quality.

From the volume and mass of the sun, the average density of the sun can be calculated as 1.409 g/cm? , about 0.26 times the average density of the earth. The acceleration of gravity on the surface of the sun is equal to 2.7398? 10 cm/s, which is about 28 times the acceleration of gravity on the earth's surface. The escape velocity of the sun's surface is about 6 17.7km/s, and the velocity of any neutral particle must be greater than this value in order to escape from the sun's gravity and run into space.

4. solar halo

Solar halo is an atmospheric optical phenomenon, which is formed by the refraction or reflection of ice crystals when sunlight passes through cirrostratus. When light enters the ice crystals in cirrostratus, it is refracted twice and dispersed into light of various colors in different directions. When there is cirrostratus, there are countless ice crystals floating in the sky. Ice crystals in the same circle around the sun can refract the same color light into people's eyes, forming a halo of internal infrared violet. When a cirrostratus composed of ice crystals appears in the sky, one or more colored halos of internal infrared violet centered on the sun often appear around the sun, and sometimes many colored or white light spots and arcs appear. These halos, spots and arcs are collectively called halos.