COLORS OF NATURE
PERCEPTION OF COLOR
People perceive color through a process known as trichromacy or trichromatism in which specialized cells are used in our eyes. Three different types of cones are present, each sensitive to a different wavelength and corresponding to various colors:
★ S-cones (short-wavelength cones): These are the most suited for light with a short wavelength that is referred to as blue. They are mostly activated by light with a golf-length of between 420 and 440 nanometers.
★ M-cones (medium-wavelength cones): are the most suitable for light, with a standard wavelength that is referred to as green. They react to light with a golf-length of around 530–540 nanometers.
★ L-cones (long-wavelength cones): are the most conducive to light with a long golf-length that is referred to as red. They are activated by light with a golf-length of at least 560-580 nanometers.
When light enters our eyes, it interacts with these cones. Depending on the strength of light at various wavelengths, they are stimulated to different degrees. The signals from the cones are then transmitted to the brain via the optic nerve.
The brain processes the signals and combines the information to create our perception of color. For example, when both the L-cones and M-cones are equally stimulated, our brain perceives the color yellow.
When all three cone types are stimulated in varying degrees, we perceive the entire visible spectrum including a wide range of colors.
It is important to keep in mind that differences in cones’ sensitivity and distribution of cones might affect how each person perceives color. Some people experience color blindness, which makes colors less responsive or absent, making it difficult to distinguish between colors. The intricate interaction between light, cones and the brains puts us in a position to access a wide range of vibrant colors.
Colors are created naturally by the interaction of light and matter. The colors we see are the outcome of the interaction between various materials and light at the microscopic level. Here are a few ways that colors in the natural world are perceived:
Light Source:
A light source, such as the sun or artificial light, that emits electromagnetic waves of varied wavelengths is the first step in the sense of color. In the visible spectrum, these wavelengths correspond to various hues.
The Human Eye:
The intricate optical system in the human eye allows us to observe our surroundings by capturing light. It is made up of a number of structures, such as the cornea, iris, lens, and retina.
Retina and Photoreceptor Cells:
At the back of the eye, there is a layer of light-sensitive tissue called the retina. Rods and cones are the two primary subtypes of photoreceptor cells found there.
These photoreceptors are concentrated around the macula, which is the functional center of the retina and is located close to the retina’s center. Different kinds of photoreceptors are used by the macula to give high-resolution, color vision.
Rod cells:
have nothing to do with color perception and are in charge of low-light vision. Rods have a greater surface area, are formed like cylinders, are highly sensitive to light, are used for night vision, have poor clarity of sharp vision
and are not present in the central fovea.
The fovea centralis is a tiny central pit in the eye made up of densely clustered cones. It is situated in the retina’s macula lutea.
The parafovea stretches to a radius of 1.25 mm from the central fovea, and the perifovea is located at a radius of 2.75 mm from the fovea centralis.
The word “fovea” is a Latin word for “pit.” We can see better in low light thanks to their excellent sensitivity to light intensity.
Cone cells:
In a human eye, there are roughly six to seven million cones, conical in shape, less sensitive to light, localized at the central fovea, and contribute in color vision. They function best in bright light environments and make color vision possible.
There are Red (S-cones), green (M-cones) and blue (L-cones). They are each sensitive to a different range of light wavelengths. We are able to distinguish a variety of colors because of them.
Color Perception:
Light that enters the eye and hits the retina activates cones that are sensitive to particular light wavelengths.
The optic nerve then carries the electrical signals from the cones to the vision processing areas of the brain.
Brain Processing:
In order to perceive multiple colors, the brain integrates the data it receives from the cones. A key component of processing and encoding the data relating to color perception is the visual cortex in the back of the brain.
Rainbows
When sun rays are fractured (bent) and reflected in the atmosphere by raindrops, rainbows can form.
The predominant colors of a rainbow, from top to bottom, are red, orange, yellow, green, blue, indigo, and violet. The process of forming a rainbow involves the following optical phenomena with numerous visual differences:
★ Sunlight:
for a rainbow a light source is required. Sunlight appears white to us, but it actually consists of many colors with various wave lengths.
★ Refraction:
happens when sun Rays enters a raindrop. when light transitions between different media. As in crossing from air to water. The light moves and changes direction as the waterdroplets penetrate a heavier material
★ Dispersion:
is the splitting of light into its complementary colors by each color’s various wavelengths. This occurs because each wavelength is broken under a slightly different angle, causing the colors to separate from one another.
★ Internal reflection:
after dispersion, internal reflection of the light occurs in the droplets. Some light rays turn back toward the interior of the droplet and are pushed toward the point of inflow.
★ Exit and refraction: in the end, the refracted and internally reflected light rays exit the raindrop. As the rays leave the droplet, they undergo another refraction, bending the wavelengths again as they transition from water back to air.
It is important to understand that each droplet contributes to the formation of a unique rainbow and that a collection of raindrops forms the entire rainbow. A multiple or double rainbow can also occur when light undergoes multiple internal reflections within the raindrops.
Halos
Halo’s are optical anomalies that appear when there are air ice crystals and light interacts with them. These crystals are present in large-headed clouds, such as cirrus clouds.
Halos frequently appear as heavy rings or boulders circling the sky or earth. Here is a description of how they emerge:
★ Ice crystals:
Halo’s are created when sunlight or moonlight interacts with airborne ice crystals. These prismatic crystals can manifest in a variety of shapes, including spheres/plates, columns, or hexagonal prisms. Refraction: similar to the breking that occurs when light travels through droplets and forms a rainbow, refraction of light occurs whenever light travels through these ice crystals. The hexagonal shape of the ice crystals ensures that specific wavelengths of light are absorbed.
★ Refraction: similar to the refraction that occurs when light travels through droplets and forms a rainbow, this also occurs whenever light travels through these ice crystals. The hexagonal shape of the ice crystals ensures that specific wavelengths of light are absorbed.
★ Angle of incidence and deflection:
The angle where the light enters the crystallized droplet and the angle where it leaves the crystallized droplet reveals the deflection of the light stream. Different colors of lights have different wavelengths and are consequently refracted at slightly different angles.
★ Internal reflection:
When the light is refracted, it can undergo internal reflection within the ice crystal. The light may bounce off the interior of the crystal multiple times before eventually exiting.
★ Formation of halo components:
the combination of refraction and internal reflection creates specific angles at which The light exits the ice crystal. This results in the formation of different halo components such as:
the 22-degree halo, the 46-degree halo, and the rare 9-degree halo.
– The 22-degree halo is the most common and appears as a circular ring around the Sun or Moon at approximately 22 degrees from their position. It is typically bright and displays a reddish inner edge and a bluish outer edge.
– The 46-degree halo is larger and more faint than the 22-degree halo. It forms a larger ring around the Sun or Moon at approximately 46 degrees from their position.
– The 9-degree halo is much rarer and forms a smaller inner ring around the Sun or Moon at approximately 9 degrees from their position.
★ Other halo-phenomena:
Depending on the exact origin and shape of the ice crystals, additional halo-phenomena such as:
– a tangent arc (is a halo that touches a circular halo).
– a sundog (or parhelion).
– A circumzenithal arc (is an upside-down rainbows or Bravais arcs 46° above the Sun. It forms a quarter of a circle that has a center convex centered on the zenith. It is called “a smile in the sky.”)
It is important to note that halo’s are typically seen in cloudy environments and on high terrain where ice crystals are more common. They may also occur in conjunction with other atmospheric optical effects, causing beautiful images to appear on the sky’s surface.
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★ ᴼᵖᵉⁿᴬᴵ. “ᴴᵒʷ ᵈᵒ ʰᵘᵐᵃⁿˢ ᵖᵉʳᶜᵉⁱᵛᵉ ᶜᵒˡᵒʳ?” cʰᵃᵗᴳᴾᵀ, ⁰⁹ ᴶᵘˡʸ₂₀₂₃.
★ ᴼᵖᵉⁿᴬᴵ. “ᴴᵒʷ ᵈᵒ ᶜᵒˡᵒʳˢ ᵒᶜᶜᵘʳ ⁱⁿ ⁿᵃᵗᵘʳᵉ?”cʰᵃᵗᴳᴾᵀ, ⁰⁹ ᴶᵘˡʸ ₂₀₂₃.
★ ᴮʳⁱᵃⁿ ᴰᵘⁿᵇᵃʳ. “ᴰⁱˢᶜᵒᵛᵉʳⁱⁿᵍ ᶜᵒˡᵒʳ ʷⁱᵗʰ ᵃ ᵖʳⁱˢᵐ. ᴾᵃʳᵗ ᵒᶠ: ᴼᵖᵗⁱᶜˢ: ᴸⁱᵍʰᵗ, ᶜᵒˡᵒʳ, ᵃⁿᵈ ᵀʰᵉⁱʳ ᵁˢᵉˢ ᴱᵈᵘᶜᵃᵗᵒʳ ᴳᵘⁱᵈᵉ.” ᴺᴬsᴬ sᵀᴱᴹ ᴱⁿᵍᵃᵍᵉᵐᵉⁿᵗ, ₂₀₀₀.
★ ᴼᵖᵉⁿᴬᴵ. “ᴴᵒʷ ᵈᵒ ʳᵃⁱⁿᵇᵒʷˢ ᵒᶜᶜᵘʳ?” cʰᵃᵗᴳᴾᵀ, ⁰⁹ ᴶᵘˡʸ ₂₀₂₃.
★ ᴼᵖᵉⁿᴬᴵ. “ᴴᵒʷ ᵈᵒ ᴴᴬᴸᴼ’ˢ ᵒᶜᶜᵘʳ?” cʰᵃᵗᴳᴾᵀ, ⁰⁹ ᴶᵘˡʸ ₂₀₂₃.
★ ᴺⁱᵃᵐʰ ᴳᵒʳᵐᵃⁿ. “ᴾʰᵒᵗᵒʳᵉᶜᵉᵖᵗᵒʳˢ.” ᴷᴱᴺᴴᵁᴮ, ²¹ ᴼᶜᵗᵒᵇᵉʳ ²⁰²².
★ ᵂⁱᵏⁱᵖᵉᵈⁱᵃ. “Fᵒᵛᵉᵃ ᶜᵉⁿᵗʳᵃˡⁱˢ.” ᵂⁱᵏⁱᵐᵉᵈⁱᵃ Fᵒᵘⁿᵈᵃᵗⁱᵒⁿ, ²⁰ ᴹᵃʸ ²⁰²³. cʳᵉᵃᵗⁱᵛᵉ cᵒᵐᵐᵒⁿˢ ᴬᵗᵗʳⁱᵇᵘᵗⁱᵒⁿ⁻sʰᵃʳᵉᴬˡⁱᵏᵉ ᴸⁱᶜᵉⁿˢᵉ ⁴.⁰.
★ ᵂⁱᵏⁱᵖᵉᵈⁱᵃ. “cᵒⁿᵉ ᶜᵉˡˡ.” ᵂⁱᵏⁱᵐᵉᵈⁱᵃ Fᵒᵘⁿᵈᵃᵗⁱᵒⁿ, ¹⁸ ᴶᵘˡʸ ²⁰²³. cʳᵉᵃᵗⁱᵛᵉ cᵒᵐᵐᵒⁿˢ ᴬᵗᵗʳⁱᵇᵘᵗⁱᵒⁿ⁻sʰᵃʳᵉᴬˡⁱᵏᵉ ᴸⁱᶜᵉⁿˢᵉ ⁴.⁰.
