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Slawomir wrote:I am wondering whether sunlight being predominantly yellow-green has something to do with chlorophyll having green colour as well.

Cousin Ricky wrote:

Slawomir wrote:
I am wondering whether sunlight being predominantly yellow-green has something to do with chlorophyll having green colour as well.

It doesn’t. It is not to a plant’s advantage to reflect away the predominant wavelengths of its energy source, so the colors are probably just a coincidence. Most plants have such a low albedo anyway, that the fact that they reflect slightly more green than other wavelengths is of little consequence.

• Sunlight being predominantly yellow-green may have something to do
  with flowers & fruits having attractive blue/violet & yellow/red colors:

https://en.wikipedia.org/wiki/Anthocyanin wrote:

[b][color=#0000FF]Superposition of spectra of chlorophyll a and b with oenin, a typical anthocyanin, in an acidic solution. While chlorophylls absorb in the blue and yellow/red parts of the visible spectrum, oenin absorbs mainly in the green part of the spectrum, where chlorophylls do not absorb at all.[/color][/b]

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<<Anthocyanins (from Greek: ἀνθός (anthos) = flower + κυανός (kyanos) = blue) are water-soluble vacuolar pigments that may appear red, purple, or blue depending on the pH. They belong to a parent class of molecules called flavonoids synthesized via the phenylpropanoid pathway; they are odorless and nearly flavorless, contributing to taste as a moderately astringent sensation. Anthocyanins occur in all tissues of higher plants, including leaves, stems, roots, flowers, and fruits.

In flowers, bright-reds and -purples are adaptive for attracting pollinators. In fruits, the colorful skins also attract the attention of animals, which may eat the fruits and disperse the seeds. In photosynthetic tissues (such as leaves and sometimes stems), anthocyanins have been shown to act as a "sunscreen", protecting cells from high-light damage by absorbing blue-green and ultraviolet light, thereby protecting the tissues from photoinhibition, or high-light stress. This has been shown to occur in red juvenile leaves, autumn leaves, and broad-leaf evergreen leaves that turn red during the winter. The red coloration of leaves has been proposed to possibly camouflage leaves from herbivores blind to red wavelengths, or signal unpalatability, since anthocyanin synthesis often coincides with synthesis of unpalatable phenolic compounds

In addition to their role as light-attenuators, anthocyanins also act as powerful antioxidants. However, it is not clear whether anthocyanins can significantly contribute to scavenging of free radicals produced through metabolic processes in leaves, since they are located in the vacuole and, thus, spatially separated from metabolic reactive oxygen species. Some studies have shown hydrogen peroxide produced in other organelles can be neutralized by vacuolar anthocyanin.
Light absorbance

The absorbance pattern responsible for the red color of anthocyanins may be complementary to that of green chlorophyll in photosynthetically active tissues such as young Quercus coccifera leaves. It may protect the leaves from attacks by plant eaters that may be attracted by green color.>>

rj rl wrote:Why are the missing patches all blurry? I thought the absorption occurs only at very certain wave-lengths and not at wave-length +/- couple nanometers.

Chris Peterson wrote:

rj rl wrote:Why are the missing patches all blurry? I thought the absorption occurs only at very certain wave-lengths and not at wave-length +/- couple nanometers.

While atomic absorption and emission spectra are associated with specific electron transitions which result in extremely narrow lines, in the real world we're usually looking at thermal sources, and the atoms involved have a lot of motion. So the lines are broadened by the Doppler effect- the actual emission or absorption observed depends on the velocity of the atom towards or away from us. This blurs the lines.

Dad is watching wrote:

Chris Peterson wrote:While atomic absorption and emission spectra are associated with specific electron transitions which result in extremely narrow lines, in the real world we're usually looking at thermal sources, and the atoms involved have a lot of motion. So the lines are broadened by the Doppler effect- the actual emission or absorption observed depends on the velocity of the atom towards or away from us. This blurs the lines.

Does this mean that the makeup various layer of the suns atmosphere (photosphere) can be determined by the blurring of the absorption lines? Wherein the more volatile and active layers (blurred absorption lines) can show which elements are located at which various 'altitudes' of regions?

Cousin Ricky wrote:

Slawomir wrote:I am wondering whether sunlight being predominantly yellow-green has something to do with chlorophyll having green colour as well.

It doesn’t. It is not to a plant’s advantage to reflect away the predominant wavelengths of its energy source, so the colors are probably just a coincidence. Most plants have such a low albedo anyway, that the fact that they reflect slightly more green than other wavelengths is of little consequence.

aileen wrote:I really like the chlorophyll idea. Maybe in the past plants had all different colors, but only the green/yellow ones were supported by most energy and were selected by evolution. But this is just a bold guess.

Here is my two cents: maybe the spectrum is also dependent on where the sunlight is collected and measured. If the experiment was run on the earth, then the sunlight had already travelled a very long distance and some frequencies might have been attenuated (sunlight was filtered by the substances in space). And that's why we are not seeing all the colors. But if we collect sunlight on the sun, then spectrum might be more complete.

Chris Peterson wrote:

aileen wrote:
I really like the chlorophyll idea. Maybe in the past plants had all different colors, but only the green/yellow ones were supported by most energy and were selected by evolution. But this is just a bold guess.

Certainly, you need to consider evolutionary processes. But such processes rarely yield ideal solutions. Photosynthesis is a complex process and probably only evolved once. And the process using chlorophyll primarily uses red light. Different plant colors have evolved, in part to help make more efficient use of other parts of the spectrum. But the underlying process for all is not optimized for the color of the Sun.

neufer wrote:

Chris Peterson wrote:Certainly, you need to consider evolutionary processes. But such processes rarely yield ideal solutions. Photosynthesis is a complex process and probably only evolved once. And the process using chlorophyll primarily uses red light. Different plant colors have evolved, in part to help make more efficient use of other parts of the spectrum. But the underlying process for all is not optimized for the color of the Sun.

http://www.livescience.com/1398-early-e ... gests.html

Beecroft wrote:Apparently the sun supports marriage equality! (With a few colors unrecognized...)

Animal of Stone wrote:

Beecroft wrote:Apparently the sun supports marriage equality! (With a few colors unrecognized...)

You bet. Apparently the sun supports all life on this planet. And congratulations to the Americans and APODs timing is perfect !!

geckzilla wrote:

Animal of Stone wrote:You bet. Apparently the sun supports all life on this planet. And congratulations to the Americans and APODs timing is perfect !!

There are some exceptions to this living around deep ocean hydrothermal vents. Edit: hydrothermal? Geothermal? Volcanic thingies...