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ARC TANGENT SUPERIEUR [1 record]
Record 1 - internal organization data 2004-09-13
Record 1, English
Record 1, Subject field(s)
- Atmospheric, Climatic and Meteorological Phenomena
Record 1, Main entry term, English
- upper tangent arc
1, record 1, English, upper%20tangent%20arc
correct
Record 1, Abbreviations, English
Record 1, Synonyms, English
Record 1, Textual support, English
Record number: 1, Textual support number: 1 CONT
The above photo shows a halo phenomenon known as the upper tangent arc. When cirrus clouds contain columnar ice crystals aligned so that their axes are all in a horizontal direction, this type of arc may be produced. A characteristic of this arc-shaped patch of light is that it's directly above the Sun (it bends upward away from the Sun), and it's approximately 22 degrees away from the Sun itself - about 2 fists held at arms length. 1, record 1, English, - upper%20tangent%20arc
Record number: 1, Textual support number: 2 CONT
The 22° halo is most common, but other halo forms are sometimes seen. The tangent arcs to the 22° halo can appear if the sun's declination is less than 32°. One is called the lower tangent arc to the 22° halo, and the other is the upper tangent arc to the 22° halo. The shape of these tangent haloes depends upon the sun's declination. If the sun is close to the horizon, the two upper arcs angle sharply away from the 22° halo. As the sun rises higher in the sky, the tangent arcs move toward the 22° halo. When the sun's declination reaches 32°above the horizon, the lower and upper tangent arcs make contact, and the resulting ring is called the circumscribed halo. It touches the 22° halo above and beneath the sun. When the sun is just above 32°the circumscribed halo resembles a double oval. As the sun rises higher it becomes increasingly circular and draws nearer to the 22° halo. When the sun's declination exceeds 70°, the circumscribed arc nearly coincides with the 22° halo. 2, record 1, English, - upper%20tangent%20arc
Record 1, French
Record 1, Domaine(s)
- Phénomènes météorologiques, climatiques et atmosphériques
Record 1, Main entry term, French
- arc tangent supérieur
1, record 1, French, arc%20tangent%20sup%C3%A9rieur
correct, masculine noun
Record 1, Abbreviations, French
Record 1, Synonyms, French
- arc supérieur tangent 2, record 1, French, arc%20sup%C3%A9rieur%20tangent
correct, masculine noun
Record 1, Textual support, French
Record number: 1, Textual support number: 1 CONT
Un peu au-dessus ou au-dessous de l'astre lumineux [soleil], à la distance de 22 degrés, on peut fréquemment voir des arcs supérieurs et inférieurs tangents au petit anneau. En fait, on observe plus souvent les arcs supérieurs; ils ont souvent de belles couleurs. [...] Sur l'image suivante, on voit un arc tangent supérieur. 2, record 1, French, - arc%20tangent%20sup%C3%A9rieur
Record 1, Spanish
Record 1, Textual support, Spanish
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