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Rainbows
(彩虹) are one of the most beautiful works that nature creates. {#blank#}1{#/blank#} If
you've ever seen one, consider yourself lucky.
Rainbows
can be seen when light passes through raindrops, says Kristin Calhoun, a
research scientist studying the conditions of weather.
When
sunlight passes through raindrops, the light bends, as it enters a droplet. As
it leaves the droplet, the light separates into different wavelengths (波长). {#blank#}2{#/blank#} The seven colors — red, orange, yellow, green, blue, indigo
and violet — bend in seven different directions. Red light, for example, bends
in a different way than violet light. {#blank#}3{#/blank#} It also explains why rainbows look
like an arc (弧). Sometimes, however, rainbows can
actually form a circle that you can see in a plane with the right conditions.
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"There is an even better chance when the sun is at a lower level, early or
later in the day," Calhoun says. And another key is to face the rain and
have your back to the sun.
{#blank#}5{#/blank#}
"Small showers and storms often form in late afternoon in this area,"
Calhoun says. "These types of showers often produce heavy rain, but remain
isolated (孤立的) over the center of the island."
A．There are lots of
stories relating to rainbows.
B．Rainbows are created
by light through raindrops.
C．And each wavelength
appears as a different color.
D．With the conditions
just right, Hawaii gets lots of rainbows.
E．The best time to
catch a rainbow is when it's sunny and raining.
F．But they can be seen
only if you are in the right place at the right time.
G．This is why the
person on the ground sees each color at a different location.
