I write this blog post to celebrate the last day of winter in the southern hemisphere, although I for one will be just a tad-bit sad to see this season of ‘green’ come to an end because soon the dreaded heat will be upon us.
Anyone who knows me also knows that I absolutely love Clouds and Rainbows. I have been known to stop the car in transit just to take a ‘happy snap’ of them and I would probably have more photos of them in my phone/tablet galleries than any other subject matter (including my hubby and kids)!
Rainbows are one of the most beautiful sights in nature simply because of the somewhat magical appearance of its colourful arch splashed upon a grey-blue-sky canvas. For me they are the best kind of Colour Therapy, especially if you live in a drought prone area where rain is always welcome.
So what constitutes a rainbow apart from us seeing colours in the sky? A rainbow is nothing more than a massive curved banded-coloured spectrum that appear in the sky once the clouds start to clear and sunlight strikes the raindrops that are falling to the earth.
The raindrops act as a prism because they have the ability to break up light therefore allowing the colours to emerge from the prisms to form a band of stripes which we call a spectrum.
In other words, sunlight, or ordinary white light which is really made up of a mixture of all the colours in a rainbow is broken up into different colours and we can only see the colours of red, orange, yellow, green, blue and purple because of different wave lengths of light which bends and travels onward to your eyes so that you can easily see and differentiate the many colours.
The shortest wave lengths that we can detect are the purple colours of violet and indigo. Then the waves of light lengthen into the colours of blue and green and then onto the colours of yellow, orange and red. The longest visible light waves are a deep red colour.
However, when you look into white light you are actually seeing all of the colours of the rainbow blended in together because your eyes are not able to distinguish between the different colours of the rainbow unless they pass through some material that is able to separate them first.
It is for this simple reason that a rainbow is only seen during showers, when droplets of rain is falling and the sun is shining at the same time.
When sunlight enters a droplet of water, it is broken up just as if it had entered a glass prism.
So inside the drop of water, we already have the different colours going from one side of the drop to the other.
Some of this coloured light is then reflected from the far side of the droplet, back and out of the droplet.
The light comes back out of the droplet in different directions, depending on the colour and when you look at these colours in a rainbow, you will always see them arranged with red at the top and violet at the bottom of the rainbow.
What happens is that the white light is broken up into the different wave lengths that are seen by our eyes as red, orange, yellow, green, blue, indigo and violet.
In a rainbow, the sunlight is refracted when it goes into the droplets of water. It is reflected inside them and refracted again as it passes out.
The colour seen by an observer will depend on the angle at which he looks at each droplet.
It also helps if you are standing in the middle ground with the sun behind you and the raindrops falling in front of you to be able to see a rainbow properly.
The sunlight shines over your shoulder into the raindrops which act as prisms breaking up the light into a spectrum or a band of colours. The sun, your eyes and the centre of the rainbow’s arch needs to be virtually all in a straight line for you to see a complete unbroken rainbow.
If the sun is up too high in the sky, it is impossible to be able to make such a straight line and that is the usual explanation given as to why you would normally only see rainbows in the early morning or late afternoon.
From the ground, a rainbow looks like an arch, but apparently from an aeroplane, it looks just like a circle (unfortunately I have not been lucky enough to see one from a plane).
With that said, there are other ways in which you can see the colours of the rainbow apart from the big curved spectrum arch in the sky.
The water drops in the spray from a garden hose or sprinkler will often make a rainbow on a sunny day. Just put your finger at the end of the garden hose so that the water spray fans out and aim it towards the sun. You should see a small colourful rainbow arch.
Also if you were to look up at a waterfall with the sun behind you, you would be able to see a rainbow arch formed by the rays of sunlight that has been split up by the water spray droplets.
You can also usually see the colours of the rainbow in soap or detergent bubbles as well as in the thin patches of oil found on a wet road.
If you can think of any more ways to see a rainbow, please add them to the comments section down below.
Make Yourself Your Very Own “Fake Rainbow”
DIY Rainbow Maker No. 1
You can easily make colours appear on clear plastic, but you will need a pair of Polaroid sunglasses.
Shine a bright light (a torch will do) at a tape cassette box (if you can still find one or if not, another clear plastic container/box will work just as well) and then look at it through a pair of Polaroid sunglasses.
You should see a rainbow effect made up of bright colours.
The Polaroid sunglasses cut out some of the colours that make up white light and you see the colours that are left.
DIY Rainbow Maker No. 2
You can make up all of the colours in a rainbow by mixing red and green light, green and blue light or blue and red light.
Combining all three colours creates white light.
Red, green and blue are called the primary colours of light.
DIY Rainbow Maker No. 3
Paint, ink and crayons are like all other objects – they only reflect the light that falls on them.
You can make all the rainbow colours by mixing red and yellow, yellow and blue, or blue and red paint.
Red, yellow and blue are the primary colours of paint.
DIY Rainbow Maker No. 4 – Bubble Dome
Tape a torch to the bottom of a clear plastic container, bowl or box lid.
Hold it upright and spoon a little bubble mixture (or detergent) onto the container, bowl or box lid.
Stick a straw into the bubble mix and gently blow some bubbles to make a bubble dome.
Switch on the torch and then go into a dark room with the torch still on.
Take a good look at the bubbles.
What colours do you see swirling about?
Do the colours ever change?
What colours do you see just before a bubble pops.
Note:
All bubbles are a sandwich of soap and water.
As they reflect light from a torch you can see the colours of the rainbow swirling on their walls. If you blow gently on a bubble, the colours change as the walls get thinner.
When the bubble walls are at their thinnest the colours disappear, so just before a bubble pops, it appears to go black.
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