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How to Shop for Satellite TV Receivers and Dishes
Let’s face it, Internet readers, most of us are guys. And as red-blooded American guys, we all have men’s desires, men’s needs. Don’t play coy. You know what I’m talking about. We want it faster, more creative, more imaginative, and not to put too...
Hurricane Fact Sheet
Hurricane Fact Sheet A hurricane is a large whirling storm that usually measures 200 to 500 miles (320 to 800 km) across. On the average each year, six Atlantic hurricanes occur. Sustained winds of 100-150 mph (160-240 km/h) occur with a typical...
I Wouldn't Change a Thing
CHAPTER ONE: From Riches to Rags: When I look back upon my life in this round of the soulful experience I have enjoyed so much; there are many things that seem almost too good to be true. I have chosen to be a very unusual ‘bird’ or a weird duck to...
Probability - Fact or Fiction
Probability – Fact or Fiction So what is the chance that a coin will land heads when flipped? Scientists say there is a 50% chance. Is this necessarily so though? From reading my other articles it should be clear that one theory of our universe...
Real Ghosts, Ghost Hunting, and Quantum Physics
One of the benefits of a lifetime of afterlife communication is that I know a lot about ghosts … what they are and what they're not. For instance, they're not "caught between worlds." And they don't need us to help them "move on." They're exactly...
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How strange! The sky is blue!
Look up! Just do it. What do you see? Stupid question, eh? You see the ceiling of course. When you look upwards during a sunny day while picnicking however, you see the blue sky. Ever wondered why the sky is not green nor but blue?
Before answering this question, let’s go back to the basic physics of light. Sorry, but here I go…
Light is a kind of energy, which travels in waves. In fact, light is a wave of vibrating electric and magnetic fields. Light forms only one small part of a larger range of vibrating electromagnetic fields called the electromagnetic spectrum. Electromagnetic waves travel through space at an amazing 300 00km/s. Therefore this is also the speed of light.
When you see white light from the bulb, you are actually seeing the seven colours of the rainbow! This is because white light consists of a combination of these seven colours.
Each of these colours has a different wavelength, frequency and energy. Wavelength is the distance between the crests of the waves. The frequency is the number of waves that pass by each second. Note that the longer the wavelength, the lower the frequency and the less energy it contains.
·Violet: Shortest wavelength, highest frequency and energy
·Red: Longest wavelength, lowest frequency and energy
Now back to our main topic. That blue colour of the sky is due to an effect known as the Rayleigh scattering. As light from the sun moves towards Earth’s atmosphere, not all the colours are actually able to pass through that atmosphere. Most of the longer wavelength colours do pass (red, orange and yellow for sure) but
the shorter wavelength ones however are mostly absorbed by gas molecules found in the atmosphere. Absorbed blue light is then bounced back (radiated would be a better word) in all directions. This makes the shy to appear blue!
You would however ask me why it’s the blue rays, which get scattered, and not the indigo nor the violet rays (the other colours pass through the atmosphere remember – there’s also blue that pass through but it then gets scattered). Well in fact, the shorter the wavelength, the more the colour gets scattered. Violet, which has the shortest wavelength of all colours of the rainbow thus gets scattered more than blue rays do. Our eyes however are much more sensitive to blue than to violet and the sky therefore doesn’t appear to be violet but blue (in reality the sky is violet-indigo!).
Now do take the time making the following:
Take a look at the horizon (if you’re at the seaside) and note the sky’s colour there. No, it’s not as blue as the rest of the sky, is it? It’s much paler. This is because for the blue light to reach your eye, it has to travel more. Blue light will thus pass through more air consequently getting scattered more. Conclusion: less blue light reaches your eyes than compared to blue light from just above you.
About the Author
K.A.Cassimally is the editor in chief of Astronomy Journal and Astronomy Journal Ezine. He is also the co-founder of the RCPL Astronomy Club. K.A.Cassimally is best known for his article 'Harry Potter and the Moons of Jupiter'.
He is also Senior Columnist at BackWash.com where he writes 'Not Scientific Science'.
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