Rainbows as Superimposed Disks of Colour

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To find out more about the diagram above . . . . read on!

Rainbows as Superimposed Disks of Colour

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!

About the Diagram

Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

Have you already checked out An Introduction to Rainbows?

It is the opening page of our Rainbow Series and contains masses of useful information. This is the table of contents:

So let’s start this page with an overview of rainbows

A rainbow is an optical effect produced by illuminated droplets of water. Rainbows are caused by reflection, refraction and dispersion of light in individual droplets of rain and results in the appearance of an arc of spectral colours across the sky.

  • Rainbows only appear when weather conditions are ideal and an observer is in the right place at the right time.
  • Waterfalls, lawn sprinklers and other things that produce water droplets can produce a rainbow.
  • A rainbow is formed from millions of individual water droplets each of which reflects and refracts a tiny coloured image of the sun towards the observer.
  • It is the dispersion of light as refraction takes place that produces the rainbow colours seen by an observer.
  • If the sun is behind an observer then the rainbow will appear in front of them.
  • When a rainbow is produced by sunlight, the angles between the sun, each droplet and the observer determine which ones will form part of a rainbow and which colour each will produce.
  • Rainbows always form arcs around a centre point (called the anti-solar point).
  • The axis of a rainbow is an imaginary line drawn between the light source and observer during the period the bow is visible. The anti-solar point is on the same axis.
  • If you can see your own shadow and a rainbow at the same time, then the anti-solar point (the centre of the rainbow) is aligned with the shadow of your head.
  • Seen from the air a rainbow can appear as a complete circle. It is only because the ground around the observer gets in the way that a rainbow produced by sunlight is reduced from a circle to a semi-circle or an arc.
  • The sky inside a rainbow is brighter than on the outside because raindrops direct light there too.
  • When you see a primary rainbow, the band of red appears on the outside, followed by orange, yellow, green, blue, with violet on the inside.
  • When you see a double rainbow then the secondary rainbow is above the primary bow, it is usually less intense, and the colours are in reverse order with violet on the outside.

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Some Key Terms

Move to the next level! Check out the following terms.

Observer

A human observer is a person who engages in observation or watches something. In the presence of light, an observer ...
Read More

Rainbow

A rainbow is an optical effect produced by illuminated droplets of water. Rainbows are caused by reflection, refraction and dispersion ...
Read More

Rainbow colours

Rainbow colours are the bands of colour seen in rainbows and in other situations where visible light separates into its ...
Read More

Spectral colour

A spectral colour is a colour evoked in normal human vision by a single wavelength of visible light, or by ...
Read More

More Information

ABOUT SLIDES

Slides


All images on the lightcolourvision.org website are available for download as either slides or diagrams.

All slides share common specifications:

  • Titles: All slides have titles.
  • Backgrounds: Black, framed with a violet gradient.
  • Size: 1686 x 1124 pixels (3:2 aspect ratio).
  • Slides are available in two file formats: JPG, AI (Adobe Illustrator).

Slides are optimized for viewing on-screen or with a projector.
Diagrams are optimized for printing on A4 pages in portrait format.

ABOUT DIAGRAMS

Diagrams


All images on the lightcolourvision.org website are available for download as either slides or diagrams.

All diagrams share common specifications:

  • Titles: No titles.
  • Backgrounds: White.
  • Size: 1686 pixels wide. So all diagrams reproduce at the same scale when inserted into Word documents etc.
  • Labels: Calibri 24pt Italic.
  • Diagrams are available in two file formats: JPG, AI (Adobe Illustrator).

Diagrams are optimized for printing on A4 pages in portrait format.
Slides are optimized for viewing on-screen or using a projector.

FILE TYPES - JPG

JPG file format


Download the image at the top of this page as a JPG file:

  • All JPG images available for download are 1686px wide.
  • Text on JPG images with white backgrounds is styled as Calibri 24pt Italic.
  • If the image you need is not exactly right, download it as an AI (Adobe Illustrator) file and edit it.
  • All the images on these Resource Pages were created in Adobe Illustrator and are vector drawings.

Did you know:

  • JPG stands for Joint Photographic Experts Group who created the standard.
  • The JPG file extension is used interchangeably with JPEG.
  • JPG files can be compressed for use on websites.
  • JPG files can be placed or pasted directly into MS Office documents.

FILE TYPES - AI

AI (Adobe Illustrator) file format


Download the image at the top of this page as an AI (Adobe Illustrator) file:

  • All AI images available for download from lightcolourvision.org are 1686px wide.
  • All the images on these Resource Pages were created in Adobe Illustrator and are vector drawings.
  • Vector drawing can be scaled up or down without any loss of quality.

Did you know:

  • AI  files downloaded from lightcolourvision.org can be re-edited using Adobe Illustrator for your own personal use.
  • Adobe Illustrator can save or export AI files to other formats including PDF (.pdf), PNG (.png), JPG (.jpeg) and SVG(.svg) etc.

DOWNLOAD AGREEMENT

Download agreement

Download Agreement


Before downloading or cutting and pasting from lightcolourvision.org we ask you to agree to the following terms:

  1. All information, images and other assets displayed or made available for download on the lightcolourvision.org website are copyright. This means there are limitations on how they can be used.
  2. All information, images and other assets displayed or made available for download are solely and exclusively to be used for personal, educational and non-profit purposes.
  3. When you find the resources you need, then part of the download process involves you (the user) ticking a box to let us (at lightcolourvision.org) know we both agree how the material can be used.
  4. Please contact [email protected] before considering any use not covered by the terms of the agreement above.

If you are a student, educator or researcher you might also like to read our posts Copyright: Credit where credit’s due and Citation and bibliographies before copying and pasting material into essays, assignments or other academic work. They include advice on avoiding plagiarism and how to credit other people’s words, images and assets before submitting your work for marking or assessment. If you are confused, just ask a friendly teacher, librarian, or other member of academic staff.


Like to know more?

Please contact [email protected] if you have questions about any aspect of this project.