Fr.: arc-en-ciel primaire
The main rainbow that forms between about 40Â° and 42Â° from the
→ antisolar point
(or about 50Â° from the → antisolar point),
as viewed by the observer. The light path involves
→ refraction and a → single
→ reflection inside the water
→ droplet. If the drops are large, 1
millimeter or more in diameter, red, green, and violet are bright but
there is little blue.
rangin kamân (#)
A color effect produced by the → refraction and → internal reflection of sunlight passing through a mist of tiny spherical water → droplets in the air. The effect is visible only when the observer has his back to the Sun. It appears as a colored band at about 138° from the Sun, hence 42° from the → antisolar pint. In other words, 42° is the angle between the direction of the → incident sunlight and the → line of sight. The → primary rainbow is caused from one reflection inside water droplets; the red color appears on the top and violet on the bottom. At solar elevations higher than 42° the bow is entirely below the → horizon and therefore invisible in the sky. A full rainbow is actually a complete circle, but from the ground we see only part of it. From an airplane, in the right conditions, one can see an entire circular rainbow. A → secondary rainbow appears if the sunlight is reflected twice inside the water droplets. Secondary rainbows are fainter, and the order of the color is reversed, with red on the bottom and violet on the top. See also: → Alexander's dark band, → supernumerary rainbow.
Fr.: angle d'arc-en-ciel
The → obtuse angle between sunlight and the → line of sight. Rainbow angle = 180° minus → scattering angle. For the → primary rainbow it is 138°, and for the → secondary rainbow 130°.
Fr.: rayon d'arc-en-ciel
The sunlight incident on a tiny spherical droplet of water.
Fr.: arc-en-ciel secondaire
A fainter rainbow appearing about 10° above the → primary rainbow, as viewed by the observer. The secondary rainbow is about twice as wide, and has its colors reversed.
Fr.: arc-en-ciel surnuméraire
An additional faint arc or series of arcs just below the → primary rainbow. Supernumerary bows are caused by → interference and are more common toward the top of the bow.
→ supernumerary; → rainbow.