© Alan Dyer

Arenas Valley, New Mexico, United States of America

Latitude: 32° 47' 27'' N

Longitude: 108° 12' 20'' W

01 December 2014 1956 (Local Time)
Camera direction: towards SSE

Image P/S code: P.13.1.4.3

Image I.D.: 6050

• Images & related info Other Images Images of 1987 edition
• 

  Circumscribed halo

  This picture shows a circumscribed halo around the moon.

  A circumscribed halo is formed when the upper and lower tangent arcs link to form another halo outside of the 22° halo. This occurs only when the elevation of the sun or moon (in this case, the moon) is 32° or more above the horizon. The roughly oval halo touches the 22° halo at its highest and lowest points.

  When the light source (the sun or moon) is at an elevation greater than about 50°, the circumscribed halo gradually becomes circular, and at even higher elevations it merges with the 22° halo so that it may be difficult to tell them apart.

  When this picture was taken the elevation of the moon was 62° above the horizon and so the circumscribed halo forms a slight oval just outside of the circular 22° halo.

  The haloes here have formed due to the refraction of moonlight by ice crystals making up a thin layer of Cirrostratus cloud. Although stars are clearly visible, the complete circle of the 22° halo is evidence that there is a barely visible veil of Cirrostratus nebulosus in the sky. 

  Links in the image description will highlight features on the image. Mouse over the features for more detail.

  © Alan Dyer
  Arenas Valley, New Mexico, United States of America
  Latitude: 32° 47' 27'' N
  Longitude: 108° 12' 20'' W
  01 December 2014 1956 (Local Time)
  
  
  Camera direction: towards SSE
  Image P/S code: P.13.1.4.3
  Image I.D.: 6050
• 

  Halo display

  This extreme wide-angle photograph from Antarctica shows a 22° halo with two parhelia, or sun dogs, at 2 and 3 on either side. Circling the horizon and lying horizontally through the parhelia and the Sun is the parhelic circle at 4 and 5. At the top and bottom of the 22° halo are an upper tangent arc and a lower tangent arc, which extend around the 22° halo as a faint luminous curve to meet each other and form a circumscribed halo.   

  Links in the image description will highlight features on the image. Mouse over the features for more detail.

  © Tatsuru Fujita
  1-1 Ichibachō, Chūō-ku, Chiba-shi, Chiba-ken 260-0855, Japan
  Latitude: 77° 19' 12'' S
  Longitude: 39° 42' 0'' E
  24 December 2004 1328 (Local Time)
  
  
  Camera direction: towards NE
  Image P/S code: S.13.1.1 6
  Image I.D.: 4796