Next time you fly, ask for a window seat so you can watch for these
optical atmospheric effects described by Les Cowley, atmospheric
optics expert.
On the side of the plane opposite the sun, you may be able to spot
a glory, or bright white glow surrounded by one or more
shimmering rings of color. This can be seen only if there are
the plane within the clouds.
‘These rings are formed when light is scattered backwards by
individual water droplets in the cloud,’ says Cowley.
A second phenomenon visible from that side of the airplane is
called an opposition effect, which is a bright patch of
light moving along the ground below you. This spot is the point
where the shadow of the plane is hidden beneath the plane itself,
so the area looks brighter than its surroundings.
On the sunward side of the plane, ice halos and sub horizon halos
are visible. Ice halos ‘are rings and arcs of light caused by ice
crystals in high clouds … often rainbow-colored’ Cowley
says.
Sub horizon halos are bright lights that are a direct reflection of
the sun from millions of flat ice crystals floating in the
clouds.
If you happen to be flying during sunrise or sunset, make sure to
watch. Cowley says ‘the speed of the aircraft can make them faster
or slower than usual.’
For pictures of these sights, visit Cowley’s Web site
Atmospheric
Optics.
