As soon as light enters the atmosphere, it becomes scattered in all directions by oxygen and nitrogen molecules. Due to their natural resonance frequency being closer to blue wavelengths than reddish hues, blue light becomes more readily dispersed throughout the sky than its counterparts.
So that is why the sky appears as an intense blue during the day and takes on an amber hue at sunset and sunrise.
Blue Light
Of course, we all recognize that blue skies appear during clear weather due to Rayleigh scattering, the phenomenon responsible for dispersing longer wavelengths of visible light less efficiently than shorter ones. Rayleigh scattering is something most students learn in school.
This effect happens when light travels through a medium like air or water and causes particles to vibrate with a frequency near their natural resonant frequency, which causes them to oscillate more often and strongly for shorter wavelengths (like blue) than for longer ones ( like red).
Every time we see clouds in the sky, the light passing through them has been scattered by air currents and scattered back at us in various ways. We can observe this effect when gazing upon waterfalls, lakes, or rivers as well. To test it ourselves we can shine a beam of white light through a tank of water before inspecting what color light comes through in return.
John Tyndall first proposed that the sky is blue because its composition primarily comprises gases of oxygen and nitrogen that are easily scattered by water molecules in the air. Later, however, his theory was revised to account for shorter wavelengths being scattered more effectively than longer ones.
The explanation ultimately chosen, and now taught in schools, was that blue and violet lightwaves are more efficient at traveling through atmosphere than longer wavelengths such as red or green due to air molecules’ ability to reflect blue/violet light more readily than they can red/green lightrays. This phenomenon occurs because air molecules scatter blue/violet wavelengths more efficiently.
At sunset, the sky doesn’t always appear completely blue – sometimes even appearing reddish – due to sunrays having to pass through an incredible amount of atmosphere before reaching us. This causes light waves from the sun’s rays to reflect differently depending on their frequency space; more blue than violet frequencies tend to dominate. When combined with mirage effects as the sun slips beneath an unobstructed horizon and mirage effects as it slips back beneath, this creates the spectacular phenomenon known as blue flashes.
Red Light
As sunlight passes through Earth’s atmosphere, its path is altered by molecules in its composition – this scattering effect gives our sky its color; not all wavelengths of light are scattered equally though; those toward the violet end of the spectrum tend to be scattered more due to higher energy allowing it to bounce around more readily interacting with different particles in its geometry and geometry of particles composing Earth’s air mass.
As white sunlight enters our atmosphere, it contains all colors; blue and violet being dominant hues. But as it passes through, its wavelengths gradually shift towards red due to Rayleigh scattering effects and bulk attenuation processes in our atmosphere, giving rise to red-tinged skies at sunrise and sunset.
The color of the sky varies with atmospheric conditions such as clouds or pollution; on a cloudy day it might take on a yellowish tint while during clear nights it has more of a blue-white hue. Furthermore, its hue may darken or lighten depending on whether Saharan dust particles contaminate its atmosphere – for instance if this were to happen instead it will look much darker than otherwise.
Tyndall and Rayleigh proposed in the early 1900s that the blue color of the sky could be explained by dust particles or droplets of water in the atmosphere, leading some people to mistakenly believe that humid or foggy weather makes the sky appear bluer than usual. But scientific analysis has since determined that its hue results from oxygen and nitrogen molecules absorbing shortwavelength radiation, not dust or particles from clouds in the atmosphere.
Assuming there is no air pollution and our atmosphere is clear, the sky seems blue because our eyes are more sensitive to blue wavelengths than other colors. When our eyes detect blue-ish reflections from ocean and atmosphere combined with sunlight makes us see a blue hue on the horizon that gives the illusion that it’s the sky itself.
Yellow Light
As light from the Sun travels through Earth’s atmosphere, primarily composed of nitrogen and oxygen molecules, they scatter it in various ways depending on wavelength and particle size; shorter wavelengths (such as blue) get scattered more often than longer ones (like red), giving the sky its color.
The 1871 Rayleigh-Tyndall experiment established that atmospheric gases’ scattering of light is an integral component in creating the color of sky. To prove it, two identical glass jars filled with water and gas were placed side-by-side and allowed to mix; when sealed and shaken up more frequently, their contents mixed to produce blue hues; these observations led to multiple-scattering theory being recognized as one of the primary factors governing its hue.
Sky color arises due to air molecules being much smaller than lightwaves that hit them, especially nitrogen and oxygen molecules. Due to small particles found in atmosphere or drops of water that scatter light more strongly at blue end than red end of spectrum.
Blue light has lower frequencies than those resonating with nitrogen and oxygen molecules, so it is easier for it to push against their vibrational frequencies and cause them to vibrate in such a way as to scatter light. By contrast, red and yellow lights have higher frequencies which make this impossible; so most of the light that reaches our eyes from above is blue-toned with some red or yellow hues mixed in as well.
Light that penetrates an ocean or body of water diffuses and dissipates, contributing to why skies appear a deeper blue nearer the coast than further away, and why sunset and sunrise sky appear redder, since more light travels further through our atmosphere.
Orange Light
On Monday night in North County San Diego, several orange orbs drew national headlines when they were seen hovering above the Pacific Ocean. Some speculated they might be aliens while others suspected them of being Chinese lanterns; regardless, locals were delighted at what they witnessed and couldn’t stop talking about it!
Physics lies behind this phenomenon, which involves how gas molecules in the atmosphere scatter light. When sunlight passes through it encounters gas molecules that scatter it all around. Blue wavelengths seem to get more dispersion, leading to blue skies being apparent.
Orange and red light can even pass through the atmosphere without being scattered by gas molecules because their wavelengths are much smaller than these colors’ wavelengths.
Blue light scatters in many directions, whereas violet wavelengths are absorbed directly by molecules without getting scattered further. Human eyes are particularly sensitive to blue wavelengths; hence we perceive the sky as blue.
At further distances from the Sun, the sky appears a brighter blue due to the Sun’s rays passing through more atmospheric layers in order to reach our eyes.
Higher elevations appear to have deeper blue skies due to thinner atmospheres with fewer molecules that scatter light.
If you were on the Moon, even when it is filled with sunlight, the sky may appear black due to similarities between its atmosphere and that of Earth; therefore, shorter wavelengths (blue and violet light) from sunlight being scattered less likely reaches our eyes and don’t reach them directly. Outer space has no atmosphere whatsoever so skies there would also appear black.