Rainbow

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A double rainbow
Rainbow formation.png

A rainbow is an arc of color in the sky that can be seen when the sun shines through falling rain. The pattern of colors starts with red on the outside and changes through orange, yellow, green, blue, indigo to violet on the inside.

A rainbow is created when white light is bent (refracted) while entering a droplet of water, split into separate colours, and reflected back. A rainbow is actually round like a circle. On the ground, the bottom part is hidden, but in the sky, like from a flying airplane, it can be seen as a circle around the point opposite the Sun.

Rainbows often appear after storms, and are popular symbols for peace and harmony in many cultures.

Important[change | change source]

The rainbow effect can be seen when:

  • There are water drops in the air; and
  • The sun is giving light at the back of the observer at a low distance up or angle.

Rainbows always appear opposite the Sun: they form circles around the shadow of your head (which is the point opposite the Sun).

Rainbow in a thunderstorm that is moving away (at lake Zürich)

Sunlight is white, and is a mixture of many different colors. Water and other materials bend the different colors at different angles, some more strongly than others. This is called dispersion. By splitting up white light into separate colors, rainbows appear colorful even though the light hitting them is white.

The rainbow displays with the deepest effect in our minds take place when:

  • Half of the sky is still dark with draining clouds; and
  • The observer is at a place with clear sky above.

Another common place to see the rainbow effect is near waterfalls. Parts of rainbows can be seen some of the time:

  • at the edges of clouds lit from the back; or
  • as upright bands of spectrum in far away rain even if it does not fall on the earth.

An unnatural rainbow effect can also be made by spraying drops of water into the air on a sunny day.

The seven colors of the rainbow[change | change source]

The rainbow has no definite number of physical colors but seven are traditionally listed. Computer screens cannot show them precisely but can approximate them:

  • Red (web color) (Hex: #FF0000) (RGB: 255, 0, 0)
  • Orange (color wheel Orange) (Hex: #FF7F00) (RGB: 255, 127, 0)
  • Yellow (web color) (Hex: #FFFF00) (RGB: 255, 255, 0)
  • Green (X11) (Electric Green) (HTML/CSS “Lime”) (Color wheel green) (Hex: #00FF00) (RGB: 0, 255, 0)
  • Blue (web color) (Hex: #0000FF) (RGB: 0, 0, 255)
  • Indigo (Electric Indigo) (Hex: #4B0082) (RGB: 75, 0, 130)
  • Violet (Electric Violet) (Hex: #8B00FF) (RGB: 139, 0, 255)