The breezy air, the rainy time, and the sunny day are some of the day-to-day phenomena we observe on Earth. Some natural phenomena are essential to living, like the sunrise, sunset, air, wind, season, weather, and many more. These natural phenomena will not harm the environment. However, certain natural phenomena that impact people and their surroundings are earthquakes, tsunamis, floods, lightning, hurricanes, volcanos, etc.
Nuclear fusion in the sun results in the production of enormous amounts of energy known as solar energy. Solar energy enters Earth in the form of sunlight. Sunlight is a spectacular source of energy that we can witness and experience. In this article, let us discuss some natural phenomena due to sunlight in detail.
We know the light is one of the fundamental forms of energy responsible for many natural phenomena. Light has the ability to undergo processes like reflection, refraction, dispersion, and diffraction. Light is electromagnetic radiation, which, when it enters the Earth’s atmosphere, results in various phenomena like the formation of the rainbow, the blue colour of the sky, reddish sunset, and the formation of white clouds.
Let us learn about the formation of the rainbow.
Formation of Rainbow
The glorious display in the sky which we can see is the colourful rainbow. Rainbow is an optical phenomenon that can be seen when atmospheric conditions, sunlight, and the position of the viewer match! Usually, you can witness this natural phenomenon after it rains.
Rainbow consists of seven colours – Violet, Indigo, Blue, Green, Yellow, Orange, and Red. It is commonly abbreviated and referred to as VIBGYOR.
Refraction is the main cause of the formation of the rainbow. When the sunlight strikes the droplets of water in the atmosphere, it undergoes refraction. The refracted light bends and changes the direction of propagation. This happens since light travels slower in water than in air. The refracted light enters the raindrop, and it is reflected off again. The light gets reflected inside the droplet and undergoes total internal reflection separating into its component wavelengths. Each droplet of light acts as a prism. When the water droplets in the atmosphere disperse in sunlight, the rainbow is visible to us. The white light splits into seven colours of different wavelengths. Red is the colour with a longer wavelength, and hence it bends the least. Violet is the colour with a shorter wavelength and hence bends the most.
It’s a rare phenomenon that one can witness two rainbows. One is the primary rainbow, and the other is the secondary rainbow.
The below video helps to revise the chapter Human Eye and The Colourful World Class 10
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Blue Sky
It is normal to say that the sky appears blue in colour. Have you ever thought about why it appears blue?
When sunlight enters the Earth’s atmosphere, it gets scattered by the atmospheric particles. In the spectrum of white light, blue is the colour that has a minimum wavelength. Hence, the blue colour scatters the most and is scattered in all directions by the tiny atmospheric particles. This is the reason why the sky appears blue.
Reddish Sunset and Sunsets
At sunrise or sunset, the light rays from the sun enter the atmospheric air. Most of the blue and the proceeding lower wavelength of colours get scattered in the atmosphere. The red colour, which has the highest wavelength, remains without getting scattered and reaches our eyes. Hence, the sun is visible in reddish colour during sunrise and sunset.
The visible light is composed of various colours of different wavelengths. As we know, according to the Rayleigh scattering, the least wavelength blue colour is scattered the most. During the daytime, blue and other shorter wavelengths are merged in the atmosphere due to scattering. The red colour, which is least scattered, reaches our eyes. Hence the sun looks reddish at sunset and sunrise.
Formation of White Clouds
Water and dust are the particles associated with air. Consider λ as the relative size of the wavelength of light and the scatterer is of size a. When a << λ, the scattering of light occurs in accordance with Rayleigh scattering.
When a >> λ, all wavelengths are not scattered equally. This is seen in dust particles, raindrop, or ice particles, Hence, the clouds which have a >> λ appear white in colour.
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Watch the video and learn more about the chapter Human Eye and Colourful World Class 10
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The below video helps to revise the topic Human Eye Class 10
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Frequently Asked Questions – FAQs
Q1
Name the three phenomena which a light undergoes in the formation of a rainbow ?
Three phenomenons the light undergoes in the formation of a rainbow are:
Dispersion Refraction ReflectionQ2
Name some natural phenomena due to sunlight
Some natural phenomena due to sunlight are:
Formation of rainbow Formation of white clouds Blue colour of sky Reddish sunrise and sunsetQ3
Why is red used as a danger signal?
Red colour has the longest wavelength, and hence it is least scattered by the particles of the atmosphere. The red colour is visible over long distances and even can be seen in foggy conditions without compromising light intensity.
Q4
Does dust in the atmosphere impact the scattering of light?
Yes, dust in the atmosphere impacts the scattering of light.
Q5
Why does the moon appear red during lunar eclipse?
Due to the Rayleigh Scattering, the moon appears red in colour during the lunar eclipse.
Watch the video and find out why the colour of the sky changes when the sun sets?
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