|
The spectacular
circumhorizontal arc featured above and on the jacket of
the book commanded about a half-hour's worth of
attention on June 3, 2006 over northern Idaho with the
Sun 63° high. From a dock on Hauser Lake near Post
Falls, eyewitnesses watched the vibrant specimen unfold
due south as fall streaks of cirrus in the right place
at the right time flushed a vivid and full-toned fiery
spectrum about 46° wide. The bright broad arc parallels
the horizon and forms in ice crystal plates and columns
when the Sun is higher than 58° in the sky. Brian Plonka/The
Spokesman Review/wPn
 left:
Luminous arches stack and shimmer near Davos,
Switzerland on December 20, 2005. From bottom to top,
centered on the Sun at 12° elevation: the 22° halo, the
gull-winged upper tangent arc, the supralateral arc, all
topped by a circumzenithal arc. Appearing inside the 22°
halo is a vertical sun pillar, which ends with a faint
and very rare v-shaped Moilanen arc, and a portion of
the horizontal parhelic circle. Parhelia brighten the
sides of the 22° halo. Also easily noticeable in this
portrait is the relative dark halo interior compared to
its brighter but decreasing intensity of its outer edge.
Equipment: Nikon E4500 8 mm,100 ISO, f/7.5 at 1/537 sec.
Christian Rixen
Since halos are barely
predictable
and may appear for mere minutes or just seconds, keeping
a ready camera and a notepad is a good idea; good
quality photos and notes on the date, time, location and
duration (as well as the camera’s aperture, exposure,
film type and speed) document halo varieties and
occurrences like no other method, and can be used for
study and later analysis. And in the case of rare
phenomena, your notes may even contribute to better
scientific understanding.
Equipment.
SLR 35mm camera or digital camera; tripod. A wide-angle
lens of 24 or 28mm is good for many displays, but you
might also find good uses for a 28-200mm zoom lens and a
fisheye lens. Slow fine-grained film of 100 ISO does
well for solar and lunar halos, properly light-metered.
A polarizing filter increases the contrast between halo
and sky and can cut unwanted reflections and glares.
Composure.
Unless the cirrostratus cloud is so thick that the light from the Sun
or Moon is quite diffuse and subdued, block the Sun or
Moon with a leaf, light pole or some other object. This
not only protects your eyes, but also avoids camera lens
flares, loss of contrast and overexposure problems.
Technique.
Read your light meter with the Sun or Moon blocked, and
bracket your exposures for a better
chance at a superb shot. If the halo display is larger
than what you
can fit in the frame with your available lens, take a
series of overlapping pictures that can be assembled
into a montage. Lunar halos need longer exposures;
again, bracket your shots. A cable release helps avoid
camera motion. © Tim Herd
The
sunset flares skyward in suburban Des Moines, Iowa on
February 27, 2001, as ice crystal plates lingering in
the sky from the previous day's snowfall reflect a
column of light upward in a sun pillar. Equipment: Nikon
Coolpix 950 digital camera on Auto mode. Stan Richard |
