Spectacular Spectrums
Gloriously hued and ephemeral in nature,
rainbows are one of the most beautiful sights the skies have to offer.
They come in a wide variety of shapes, styles, sizes and yes, even
colours. These amazing arcs show what happens when Mother Nature gets
out her paintbox.
Classic rainbows
Most everyone has seen a classic, garden-variety rainbow – sometimes
in their gardens while watering their plants with a misting spray.
Natural rainbows are made up of 6 colours: red, orange, yellow,
green, blue and violet. The intensity of each colour may vary due to
atmospheric conditions and the time of day (more on that later).
Circular rainbows
The advent of powered flight and aerial photography has enabled the
magnificence of circular rainbows to be revealed to an awestruck public.
Of course, if an airplane isn’t available a really high mountain will
do.
The rainbows most of see are actually arcs of perfect circles (with
radii of exactly 42 degrees), though viewing a complete rainbow is
difficult as the ground has a habit of getting in the way.
Secondary rainbows
Primary rainbows are often accompanied by secondary rainbows that are
usually thinner and dimmer than the main rainbow. Here’s a bit of
trivia: the area between primary and secondary rainbows that appears
darker than the surrounding sky is called “Alexander’s Band”.
Secondary rainbows are remarkable for one particular characteristic:
they display the spectrum in reverse order from that of a primary
rainbow. It’s not something most people are familiar with.
Red rainbows
Red rainbows are usually seen at sunrise or sunset when the thickness
of the earth’s atmosphere filters out blue light leaving more red or
orange light for water droplets to reflect and refract. The result is a
rainbow with the more reddish end of the spectrum greatly enhanced.
Fogbows
Many fogbows display paler colours compared to rainbows and some are
mainly white. This is due to the fog being composed of exceedingly fine
water droplets.
Fogbows are much rarer than rainbows because certain narrow
parameters must align to create them. For one, the light source must be
behind the observer and low to the ground. Also, any fog to the rear of
the observer must be very thin so that sunlight can shine through to the
thicker fog in front.
Waterfall rainbows
Waterfalls kick a constant stream of mist into the air and the
atmospheric saturation goes on constantly, regardless of the weather.
This makes waterfalls excellent photographic companions to rainbows! The
above selection of images pairs some of the world’s most famous
waterfalls with some equally stunning rainbows.
A variation of waterfall rainbows are “spray bows”, formed on sunny
days when wind kicks up ocean or lake waves and the air becomes
saturated with mist and moisture.
Moonbows
Moonbows are the lunar counterpart to rainbows. They’re also much
more difficult to witness due to the requirement of a passing rainstorm
and, ideally, a bright full moon unblocked by clouds.
In the spectacular image above, the photographer used a 30-second
exposure at 4:34am in the morning, the moon being nearly full. The
bright star under the moonbow is the orange supergiant Arcturus.
- webecoist.com
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