A MOCK SUN

Evening Post, Volume CXI, Issue 114, 11 November 1930, Page 11

A MOCK SUN

BARE PHENOMENON

A party at The Pinnacles on: Sunday; were the fortunate observers of a; mock, sun, a comparatively rare solar -phenomenon. Between two and three o'clock in the afternoon'the sky. was.bright and cloar after the dispersal of the clouds. Round the sun was a circular rainbow, not quite complete, and very bright in patches. At. a different angle and overlapping tho rainbow was ' an enormous white circle which,, in places, wa» quite dazzling. .... The circular rainbow,', or coloured halo, which was seen is a phenomenon, not particularly rare. It is a halo which is always 22 degrees .from,.the sun. Since, however, it. is ".usuklly; present when the sun is bright and."high" i_n the heavens, few people as a rule notice it. It is caused by refraction effects in ice crystals at high, elevations,■.these ico crystals being the particles of which cirus cloudy are composed;.;. The whit© circle- stretching to. the' horizon.' is a much rarer phonothenon and; is .seen usually only' in high latitudes.'. "It is. caused by reflection effects .from • ice crystals of. certain shapes: as it, is duo to reflected and not refracted light, colour is absent. Where the horizontal circle, as it is called, crosses the 22 degrees halo, very bright patches of colour are seen (the colour coming from the latter), and these patches are generally referred to as mock. suns;, or parhelia. Mock suns earrsometim.es be seen in other parts of the horizontal circle. On Sunday afternoon there was a considerable amount of cirus cloud about and the conditions were favourt able for seeing mock suns.