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Rainboows

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RAINBOWS
LEARN MORE ABOUT RAINBOWS :D

What is a rainbow?
A rainbow is sunlight spread out into its spectrum of colors and diverted to the eye of the observer by water droplets.

How are rainbows formed?
Rainbows are formed when a light source passes through water droplets, and then splitting them up into many different colours by dispersion...

Where is the Sun when you see a rainbow?
Most people have never noticed that the sun is always behind you when you face a rainbow, and that the center of the circular arc of the rainbow is in the direction opposite to that of the sun. The rain, of course, is in the direction of the rainbow.

What makes the colours of the rainbow?
A rainbow is made up of seven colors - red, orange, yellow, green, blue, indigo, and violet. Actually, the rainbow is a whole continuum of colors from red to violet and even beyond the colors that the eye can see.

The colors of the rainbow arise from two basic facts:

Sunlight is made up of the whole range of colors that the eye can detect. The range of sunlight colors, when combined, looks white to the eye. This property of sunlight was first demonstrated by Sir Isaac Newton in 1666.

Light of different colors is refracted by different amounts when it passes from one medium (air, for example) into another (water or glass, for example).

How is a double rainbow formed?
Sometimes we see two rainbows at once, what causes this? We have

followed the path of a ray of sunlight as it enters and is reflected inside the raindrop. But not all of the energy of the ray escapes the raindrop after it is reflected once. A part of the ray is reflected again and travels along inside the drop to emerge from the drop. The rainbow we normally see is called the primary rainbow and is produced by one internal reflection; the secondary rainbow arises from two internal reflections and the rays exit the drop at an angle of 50 degrees° rather than the 42°degrees for the red primary bow. Blue light emerges at an even larger angle of 53 degrees°. This effect produces a secondary rainbow that has its colors reversed compared to the primary.

Why is the sky brighter inside a rainbow?
Notice the contrast between the sky inside the arc and outside it. When one studies the refraction of sunlight on a raindrop one finds that there are many rays emerging at angles smaller than the rainbow ray, but essentially no light from single internal reflections at angles greater than this ray. Thus there is a lot of light within the bow, and very little beyond it. Because this light is a mix of all the rainbow colors, it is white. In the case of the secondary rainbow, the rainbow ray is the smallest angle and there are many rays emerging at angles greater than this one. Therefore the two bows combine to define a dark region between them - called Alexander's Dark Band, in honor of Alexander of Aphrodisias who discussed it some 1800 years ago!

Did you know?

Do two people ever see the same rainbow?
Humphreys points out that "since the rainbow is a special distribution of colors (produced in a particular way) with reference to a definite point - the eye of the observer - and as no single distribution can be the same for two separate points, it follows that two observers do not, and cannot, see the same rainbow." In fact, each eye sees its own rainbow!!

What is the rainbow's distance?
It is nearby or far away, according to where the raindrops are, extending from the closest to the farthest illuminated drops along the elements of the rainbow cone.

A moon can also form a RAINBOW!!!
A full moon is bright enough to have its light refracted by raindrops just as is the case for the sun. Moonlight is much fainter, of course, so the lunar rainbow is not nearly as bright as one produced by sunlight. Lunar rainbows have infrequently been observed since the time of Aristotle or before.

Taken From: www.eo.ucar.edu/rainbows

Rainboows

i love chocolate! especially at Sunday, January 24, 2010 | back to top