Sky blue is the color of the sky, caused by sunlight being scattered by particles in Earth’s atmosphere and scattered back toward space more often than any other color. Without an atmosphere, however, there would be no scattering of sunlight and consequently it would appear black in its place.
Many languages have distinct words to refer to blue and green colors; for instance, in Telugu they distinguish between “leaf-pacca” (pcc pacca) and neela niili (“blue”).
As sunlight travels through Earth’s atmosphere, it passes through gases and particles which scatter it in different directions depending on its wavelength; shorter wavelengths like blue and violet tend to be dispersed more than longer ones (red and green), so any remaining blue light passes straight through our eyes making for what is perceived to be blue skies.
Sunlight can appear white when passing through a prism because its light contains all of the colors of a rainbow. Once passed through a prism, light passes through it is separated into its component colors by refraction and diffusion; each hue can then be seen individually, creating the rainbow effect.
Just as sunlight looks blue when passing through Earth’s atmosphere and scattering into various directions, its light from the sun appears only as blue hued light that reaches us; any remaining energy being absorbed by its surface or other gases on Earth.
The sky appears blue because sunlight rays are scattered through air molecules and other particles in the atmosphere, and their other colors don’t reach our eyes as readily. At sunset and sunrise, however, sunlight must travel through more atmosphere compared to other times of the day; therefore more of its rays are scattered away by particles nearer to the horizon, leaving only red wavelengths behind for us to view; hence why the sky appears red at these times of the day.
As well as understanding and appreciating the science of sky color, it is fascinating to observe how humans have perceived and understood it over time. Leonardo da Vinci tried to understand why sunlight passed through wood smoke in 15th-century Italy; his notes reveal an understanding of light scattering principles.
The blue color of the sky results from atmospheric absorption and scattering of sunlight. Sunlight travels through our atmosphere on its way to our eyes, where air molecules scatter it differently to produce different hues; blue light is scattered more by air molecules, giving rise to its association with sky.
Atmospheric conditions can also form clouds that cover the sun and block its rays, dimming its light. This causes its brightness to appear less bright while darkening the sky. Furthermore, atmospheric conditions are responsible for producing rainbows; beautiful displays that feature various shades of blue and purple in an interweaved design.
Scientists still don’t fully comprehend why the sky is blue, but we do know it has to do with atmospheric conditions and sunlight. Leonardo da Vinci was curious about its hue as early as 1500 and conducted experiments that investigated how light passed through wood smoke; suggesting at least some understanding of the basic principles underlying its occurrence.
Himba language of Namibia uses one word to characterize both blue and green: buru, meaning ‘like the sky’ or ‘like grass’. Other languages distinguish shades of blue or green through adding descriptive terms – for instance Tamil uses names like paccai green (paccai) and neelam blue (neelam) to differentiate dark and light hues respectively.
No matter what your interest, this book will entice you to examine your world more closely and pose questions about it. With beautiful photographs, anecdotes from Dr Raman’s life and work, and explanation of his remarkable discovery, this is sure to engage anyone who appreciates its beauty while appreciating learning new things.
The Earth’s Surface
The planet Earth is an intricate and dynamic system, consisting of water, land, dirt, plants and rocks arranged over its surface. Canyons, mountains, valleys plains and oceans dot its surface while its shape shifts across continents as tectonic plates collide to form earthquakes volcanoes mountains – each having their own distinct ecosystem.
When sunlight hits Earth’s atmosphere, it is scattered by airborne gases and particles into various colors – blue light being scattered more than other hues, giving our sky its distinctive blue hue.
If the atmosphere didn’t exist, the Sun would shine directly onto Earth and the sky wouldn’t be blue. Instead, its hue depends on factors like cloud size, shape, composition and density – most are white while some may even be gray or blue in hue.
Numerous countries use specific words for blue and green colors; Zulu language offers one such term called luhlaza which translates as “like sky or grass.” Green in Mayan languages is called karu while blue is payne. Anthropologists have long found fascinating the Himba people’s ability to describe all hues of blue and green with just one single term: Himba means blue-green!
Sunlight requires significant energy from our Sun to bring us light and heat, with this excess energy being released back into space as radiation. This radiation causes Earth’s surface temperature to fluctuate; warmer regions above its surface while cooler ones lie beneath.
One effective way of explaining why the sky is blue is by showing students an image of Earth from space. While it appears smoother than a billiard ball at first glance, closer examination reveals mountain ranges and other features that contribute to its blue hue.
The sky is blue because air molecules scatter blue light more than other colors, an effect known as Rayleigh scattering. If you were watching clouds through a window from outside, their passage might look like streaks of blue – Leonardo da Vinci witnessed this effect and wrote about it in his notebooks; his explanation may not have been as scientific but provided good context for future discussions on it.
Clouds, haze or pollution can make the sky appear blue as they cause light to scatter more than it would in an atmosphere with clear conditions. Light scatters when it hits molecules in the air causing some wavelengths (namely blue wavelengths) to be scattered more strongly than others ( primarily red ones), leading to blue being scattered more strongly than red and hence our perceptions seeing sunlight through clouds as appearing blue when reaching our eyes from Sun rays; similar results are achieved when light passes through a prism and is separated into its constituent colors.
John Tyndall and Lord Rayleigh hypothesized that small dust particles or droplets of water in the atmosphere caused the sky to appear blue, when this idea led to the discovery that light can also be scattered this way by other gases in our atmosphere. Key here is that their size corresponds to wavelengths of light; hence they scatter blue wavelengths more readily.
If we observe the Sun shining through the atmosphere, higher altitudes will appear darker because its light must travel further to reach us. Furthermore, high humidity reduces intensity because more of its rays will likely be absorbed into the air than before.
Shelley’s poem personifies a cloud as if it were alive – an example of personification where human qualities are assigned to non-living objects. The cloud is described as the daughter of earth and water, the nursling of the sky who brings rain and shade, plays games with green fields by lashing them with hailstones while laughing about it, is playful yet cruel, is covered in blue just like its sky counterpart – which in India can often be identified with payne, the word used to refer to its hue; most visible during sunrise/sunset when sunlight travels through less of our atmosphere.