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Rabu, 19 Mei 2010

EXPLAINATION TEXT

NAME = IKKE FEBRIANI
SRN = 2201408097

HOW DO RAINBOW HAPPEN


Rainbows are optical and meteorological phenomena that cause a spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth's atmosphere. They take the form of a multicolored arc, with red on the outer part of the arch and violet on the inner section of the arch. More rarely, a secondary rainbow is seen, which is a second, fainter arc, outside the primary arc, with colors in the opposite order, that is, with violet on the outside and red on the inside.

Rainbows can be caused by other forms of water than rain, including mist, spray, dew, fog, and ice. Moreover, rainbows can have shapes other than a bow (arc), including stripes, circles, or even flames

The rainbow's appearance is caused by dispersion of sunlight as it goes through raindrops. The light is first refracted as it enters the surface of the raindrop, reflected off the back of the drop, and again refracted as it leaves the drop. The overall effect is that the incoming light is reflected back over a wide range of angles, with the most intense light at an angle of 40°–42°. The angle is independent of the size of the drop, but does depend on its refractive index. Seawater has a higher refractive index than rain water, so the radius of a 'rainbow in sea spray is smaller than a true rainbow. This is visible to the naked eye by a misalignment of these bows.

Rainbows can be observed whenever there are water drops in the air and sunlight shining from behind a person at a low altitude angle (on the ground). The most spectacular rainbow displays happen when half of the sky is still dark with draining clouds and the observer is at a spot with clear sky in the direction of the Sun. The result is a luminous rainbow that contrasts with the darkened background.

(^_^)

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