Katumbiri, The Spectrum Ribbon

The post this time is about Katumbiri. Do any of you know what Katumbiri means? Katumbiri means Rainbow in Sundanese. I’m gonna tell you everything that I obtained from my research through the encyclopedias and internet (ofc). By the way in case you don’t know, Sundanese is my ethnic, and our mother land is in West Java, Indonesia. We use Sundanese language. Okay then let’s start!

First, the reason why I picked this topic. This time’s assignment is talking about natural phenomenon, and I chose rainbow as my main topic. Why? It’s because I think rainbow has a philosophy. Rainbows always come after it rains, so I believe that happiness always come after sadness happen!

A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicoloured arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the sun.

Why do rainbows occur? And is it always after rain like the philosophy said before? Actually, rainbows occur when the temperature is very hot and coming together with some drizzle, and our position is back to back with the sun. Other than that, rainbows can be seen when it’s foggy or there are condensed vapor/some dew.

In physics, the process of the occurring of the rainbow is called natural refraction. It’s the action of disentangling some light, so it’ll become a spectrum. The sun is radiating polychromatic light, it has some colors which has different wave length and it’s being radiated at once. And somehow our eyes receive it as the white color.

When the ray of light is being refracted, the spectrum of colors inside the ray will be divided and be seen by our eyes as 7 colors. Those colors are red, orange, yellow, green, blue, violet, and purple.

If there’s a rainbow, the most ideal position to look at it is between the ray of sunlight and the sky’s dropping jade, and the observer must be back to back with the sun. The center arch, observer, and the sun must be in one straight line, then the colors will be seen sharper. Rainbows can be full circles; however, the average observer sees only an arc formed by illuminated droplets above the ground, and centred on a line from the sun to the observer's eye. From above the earth such as in an airplane, it is sometimes possible to see a rainbow as a full circle.

Other than that, there are also some myth that go alongside science clarification. Some people of Greece believe that a rainbow is a bridge that connects the earth and the heaven. It’s being used by Iris, God of Rainbow, or Hermes, God of Messages. In China the myth that grows is a rainbow is the result of stone piercing that has 5 colors that’s made by Nuwa.

In a primary rainbow, the arc shows red on the outer part and violet on the inner side. This rainbow is caused by light being refracted when entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it.

A rainbow is not located at a specific distance from the observer, but comes from an optical illusion caused by any water droplets viewed from a certain angle relative to a light source. Thus, a rainbow is not an object and cannot be physically approached. Indeed, it is impossible for an observer to see a rainbow from water droplets at any angle other than the customary one of 42 degrees from the direction opposite the light source. Even if an observer sees another observer who seems "under" or "at the end of" a rainbow, the second observer will see a different rainbow—farther off—at the same angle as seen by the first observer.

Rainbows can be observed whenever there are water drops in the air and sunlight shining from behind the observer at a low altitude angle. Because of this, rainbows are usually seen in the western sky during the morning and in the eastern sky during the early evening. The most spectacular rainbow displays happen when half the sky is still dark with raining clouds and the observer is at a spot with clear sky in the direction of the sun. The result is a luminous rainbow that contrasts with the darkened background. During such good visibility conditions, the larger but fainter secondary rainbow is often visible.

Rainbows can be caused by many forms of airborne water. These include not only rain, but also mist, spray, and airborne dew. The rainbow effect is also commonly seen near waterfalls or fountains. In addition, the effect can be artificially created by dispersing water droplets into the air during a sunny day. Rarely, a moonbow, lunar rainbow or nighttime rainbow, can be seen on strongly moonlit nights. As human visual perception for colour is poor in low light, moonbows are often perceived to be white.

There are many types of rainbow. I’ve written some of them. So check it out!

1. Supernumerary Rainbows

Supernumerary rainbow is a rainbow beneath rainbow. In this phenomenon, the colors of the rainbow is becoming more into pastel colors to the inside. A set of interference rainbows just inside the primary rainbow. Supernumerary bows occur when raindrops responsible for the main rainbow are much uniform in size.

	2. Reflected Rainbow/Reflection Rainbow

A reflected rainbow may appear in the water surface below the horizon. The sunlight is first deflected by the raindrops, and then reflected off the body of water, before reaching the observer. It is not a mirror image of the primary rainbow, since the crest of its mirror image is displaced by twice the height of the observer above the water table. The reflected rainbow is frequently visible, at least partially, even in small puddles.

The reflection rainbow appears above the horizon. It intersects the normal rainbow at the horizon, and its arc reaches higher in the sky, with its centre as high above the horizon as the normal rainbow's centre is below it. Due to the combination of requirements, a reflection rainbow is rarely visible.

Six (or even eight) bows may be distinguished if the reflection of the reflection bow, and the secondary bow with its reflections happen to appear simultaneously.

This kind of rainbow usually be seen on a wide water surfaces like lakes or rivers, where the water acts like a mirror, and the rainbow seems like it came from beneath the surface. This rainbow is kind of hard to see and can only be seen when the surface is calm and doesn’t have any ripple. 

3. Circumhorizontal arc

A circumhorizontal arc is an optical phenomenon - an ice-halo formed by the refraction of sun- or moonlight in plate-shaped ice crystals suspended in the atmosphere, typically in cirrus or cirrostratus clouds. In its full form, the arc has the appearance of a large, brightly spectrum-coloured band running parallel to the horizon, located below the Sun or Moon. As with all halos, it can be caused by the Sun as well as (but much more rarely) by the Moon. 

4. Halo

A halo (from Greek ἅλως, halōs; also known as a nimbus, icebow or gloriole) is an optical phenomenon produced by light interacting with ice crystals suspended in the atmosphere, resulting in a wide variety of colored or white rings, arcs and spots in the sky. Many halos are near the Sun or Moon, but others occur elsewhere or even in the opposite part of the sky.

Light is reflected and refracted by the ice crystals and may split up into colors because of dispersion. The crystals behave like prisms and mirrors, refracting and reflecting light between their faces, sending shafts of light in particular directions.

Other common optical phenomena involving water droplets rather than ice crystals include the glory and the rainbow.

Halo is a rainbow-like circle that appears around the sun or when the night comes or when the partial moon eclipse happens.

7. Circular Rainbows

In theory, every rainbow is a circle, but from the ground, only its upper half can be seen. The largest section of the circle normally seen is about 50% during sunset or sunrise. Viewing the rainbow's lower half requires the presence of water droplets below the observer's horizon, as well as sunlight that is able to reach them. These requirements are not usually met when the viewer is at ground level, either because droplets are absent in the required position, or because the sunlight is obstructed by the landscape behind the observer. From a high viewpoint such as a high building or an aircraft, however, the requirements can be met and the full-circle rainbow can be seen.

When sunlight and raindrops combine to make a rainbow, they can make a whole circle of light in the sky. But it’s a very rare sight. Sky conditions have to be just right for this, and even if they are, the bottom part of a full-circle rainbow is usually blocked by your horizon. That’s why we see rainbows not as circles, but as arcs across our sky. When you see a rainbow, notice the height of the sun. It helps determine how much of an arc you’ll see. The lower the sun, the higher the top of the rainbow. If you could get up high enough, you’d see that some rainbows continue below the horizon seen from closer to sea-level.

8. Secondary Rainbows

A secondary rainbow appears outside of a primary rainbow and develops when light entering a raindrop undergoes two internal reflections instead of just one (as is the case with a primary rainbow). The intensity of light is reduced even further by the second reflection, so secondary rainbows are not as bright as primary rainbows. Alternatively: fewer light rays go through the four-step sequence than the three-step sequence.

9. Red Rainbows

Red rainbows happen when the sun is on the horizon. They’re created for much the same reason that a sunset or sunrise looks red – because, when the sun is low, the blue and green of its rays are weakened by scattering during the long journey to your eyes through Earth’s atmosphere. The red light travels through more directly. Voila, you see a red rainbow. Usually it appears in the evening or morning, when the atmosphere makes a new filter so the colors of the rainbow is dominantly red.

10. Sundogs

Sun dogs (or sundogs), mock suns or phantom suns, scientific name parhelia (singular parhelion), are an atmospheric phenomenon that consists of a pair of bright spots on either horizontal side on the Sun. Sun dogs are a member of a large family of halos, created by light interacting with ice crystals in the atmosphere. They can be seen anywhere in the world during any season, but they are not always obvious or bright. Sun dogs are best seen and are most conspicuous when the Sun is close to the horizon.

11. Fogbows

Fogbows – sometimes called white rainbows, cloudbows or ghost rainbows – are made much as rainbows are, from the same configuration of sunlight and moisture. Fogbows are caused by the small droplets inside a fog or cloud rather than larger raindrops. Look for fogbows in a thin fog, when the sun is bright. You might see one when the sun breaks through a fog. Or watch for fogbows over the ocean. Because the water droplets in fog are so small, fogbows have only weak colors or are colorless.

12. Waterfall Rainbows

The same kind of light paths that create a rainbow in the sky can produce a rainbow in the spray of a waterfall. If you are looking at the rainbow in the waterfall, the sun must be behind you. The rainbow shown is a primary rainbow and is formed as a circular arc around the anti-solar point and at an anglar range of about 40° to 42°. This rainbow is in the Athabasca Falls of Alberta, Canada.

13. Fire Rainbows

Painting the sky in breathtaking brushstrokes of colour, these spectacular clouds were captured across the north of England as the sun started to set. The phenomenon, known as cloud iridescence, has been dubbed a 'fire rainbow' because of the spectrum of hues it throws out across the sky. The 'fire rainbow clouds', a fairly uncommon phenomenon, are created when sunlight passes through tiny ice crystals that form tens of thousands of feet in the air. The colours produced are similar to those seen in oil films on puddles.

14. Moonbows

Moonbows or lunar rainbows are rare natural atmospheric phenomena that occur when the Moon’s light is reflected and refracted off water droplets in the air. Moonbows are similar to rainbows, but they are created by moonlight instead of direct sunlight. Moonbows are rarer than rainbows because a variety of weather and astronomical conditions have to be just right for them to be created. Moonbows occur on the opposite side of the Moon and tend to look white to the human eye. This is because their colors are not bright enough to be perceived by the receptors in the human eye. It is possible, however, to view the colors in a moonbow using long exposure photography.

15. Twinned rainbow

A rainbow with mild twinning near its top (note the visible streaks of a rain shower at the same location), as well as supernumerary bands towards the left.

The colours in the second bow, rather than reversing as in a secondary rainbow, appear in the same order as the primary rainbow. A "normal" secondary rainbow may be present as well. Twinned rainbows can look similar to, but should not be confused with supernumerary bands. The two phenomena may be told apart by their difference in colour profile: supernumerary bands consist of subdued pastel hues (mainly pink, purple and green), while the twinned rainbow shows the same spectrum as a regular rainbow. The cause of a twinned rainbow is the combination of different sizes of water drops falling from the sky. Due to air resistance, raindrops flatten as they fall, and flattening is more prominent in larger water drops. When two rain showers with different-sized raindrops combine, they each produce slightly different rainbows which may combine and form a twinned rainbow.

16. Monochrome or Red Rainbow

Occasionally a shower may happen at sunrise or sunset, where the shorter wavelengths like blue and green have been scattered and essentially removed from the spectrum. Further scattering may occur due to the rain, and the result can be the rare and dramatic monochrome or red rainbow.

17. Circumhorizontal and circumzenithal arcs

The circumzenithal and circumhorizontal arcs are two related optical phenomena similar in appearance to a rainbow, but unlike the latter, their origin lies in light refraction through hexagonal ice crystals rather than liquid water droplets. This means that they are not rainbows, but members of the large family of halos. Both arcs are brightly coloured ring segments centered on the zenith, but in different positions in the sky: The circumzenithal arc is notably curved and located high above the Sun (or Moon) with its convex side pointing downwards (creating the impression of an "upside down rainbow"); the circumhorizontal arc runs much closer to the horizon, is more straight and located at a significant distance below the Sun (or Moon).

17. Rainbows on Titan

It has been suggested that rainbows might exist on Saturn's moon Titan, as it has a wet surface and humid clouds. The radius of a Titan rainbow would be about 49° instead of 42°, because the fluid in that cold environment is methane instead of water. Although visible rainbows may be rare due to Titan's hazy skies, infrared rainbows may be more common, but an observer would need infrared night vision goggles to see them.