by APOD Robot » Tue Dec 28, 2021 5:05 am
Sun Halo over Sweden
Explanation: What's happened to the Sun? Sometimes it looks like the Sun is being viewed through a giant
lens. In the featured video, however, there are actually millions of tiny lenses:
ice crystals. Water may freeze in the
atmosphere into small, flat, six-sided, ice crystals. As these
crystals flutter to the ground, much time is spent with their
faces flat and parallel to the ground. An
observer may find themselves in the same plane as many of the falling ice crystals near sunrise or sunset. During this alignment, each crystal can act like a miniature lens, refracting sunlight into our
view and creating
phenomena like parhelia, the technical term for
sundogs. The
featured video was taken in late 2017 on the side of a ski hill at the
Vemdalen Ski Resort in central
Sweden. Visible in the center is the most direct image of the
Sun, while two bright
sundogs glow prominently from both the left and the right.
Also visible is the bright
22 degree halo -- as well as the rarer and much fainter
46 degree halo -- also created by
sunlight refracting through atmospheric ice
crystals.
[url=https://apod.nasa.gov/apod/ap211228.html] [img]https://apod.nasa.gov/apod/calendar/S_211228.jpg[/img] [size=150]Sun Halo over Sweden[/size][/url]
[b] Explanation: [/b] What's happened to the Sun? Sometimes it looks like the Sun is being viewed through a giant [url=https://en.wikipedia.org/wiki/Lens_(optics)]lens[/url]. In the featured video, however, there are actually millions of tiny lenses: [url=http://www.its.caltech.edu/~atomic/snowcrystals/halos/halos.htm]ice crystals[/url]. Water may freeze in the [url=https://www.nasa.gov/sites/default/files/images/463940main_atmosphere-layers2_full.jpg]atmosphere[/url] into small, flat, six-sided, ice crystals. As these [url=https://en.wikipedia.org/wiki/Ice_crystal]crystals[/url] flutter to the ground, much time is spent with their [url=https://www.atoptics.co.uk/halo/orplate.htm]faces flat and parallel[/url] to the ground. An [url=http://littlefun.org/uploads/52410bb8e691b267f97d9278_736.jpg]observer[/url] may find themselves in the same plane as many of the falling ice crystals near sunrise or sunset. During this alignment, each crystal can act like a miniature lens, refracting sunlight into our [url=https://apod.nasa.gov/apod/ap100208.html]view[/url] and creating [url=http://www.atoptics.co.uk/halo/parhelia.htm]phenomena like parhelia[/url], the technical term for [url=https://apod.nasa.gov/apod/ap990823.html]sundogs[/url]. The [url=https://www.facebook.com/hakanhf/videos/10210053095156104/]featured video[/url] was taken in late 2017 on the side of a ski hill at the [url=https://www.skistar.com/en/ski-destinations/vemdalen/winter-in-vemdalen/]Vemdalen Ski Resort[/url] in central [url=http://en.wikipedia.org/wiki/Sweden]Sweden[/url]. Visible in the center is the most direct image of the [url=https://solarsystem.nasa.gov/solar-system/sun/in-depth/]Sun[/url], while two bright [url=http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/ice/sd.rxml]sundogs[/url] glow prominently from both the left and the right. [url=http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/halo.html]Also visible[/url] is the bright [url=http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/halo22.html]22 degree halo[/url] -- as well as the rarer and much fainter [url=http://www.atoptics.co.uk/halo/46hal.htm]46 degree halo[/url] -- also created by [url=http://www.atoptics.co.uk/halo/circular.htm]sunlight refracting[/url] through atmospheric ice [url=https://apod.nasa.gov/apod/ap200224.html]crystals[/url].
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