Fenomena Halo di Kuantan // Halo phenomenon in Kuantan

Kuantan, PAHANG: Kebiasaannya apa yang sering disaksikan di langit adalah pelangi. Tetapi bagi penduduk sekitar Kuantan, apa yang mereka saksikan bukan pelangi tetapi satu fenomena alam luar biasa yang mungkin tidak pernah dilihat. Kejadian kira-kira pukul 4.30 petang itu menyaksikan gelungan cahaya jingga yang tebal dan perlahan-lahan terbias sekitar kelompok awan cerah yang hampir diliputi awan mendung. Fenomena itu berlaku dalam tempoh antara lima hingga 10 minit sebelum keseluruhan kelompok awan menjadi mendung.

Lebih menghairankan, setengah jam kemudian awan gelap turut hilang dan suasana kembali normal.Jurucakap Jabatan Kajicuaca yang dihubungi berkata, fenomena berkenaan dinamakan ‘Fenomena Halo’ yang berlaku apabila cahaya matahari terserak oleh gumpalan awan.


(petikan Berita Harian)

Kuantan, PAHANG: It is normal to see a rainbow over the sky. As for the Kuantan people, it was not the latter they had seen, but a very rare phenomenon of the nature. The phenomenon had happenned around 4.30 p.m. where there was a thick optical purple-coloured light, appeared on top of a cumulonimbus cloud, which later had slowly reflected and dispersed around cumulonimbus cloud into the cirrus cloud. The rare phenomenon was in display at the sky in about 5 to 10 minutes before it turned into a black-cloudy cloud.

Amazingly, after half an hour, the cloudy cloud were gone and the sky was clear and back to normal. A spokeperson from Meteorological Centre was contacted and they claimed the phenomenon happened is known as Halo (optical phenomenon).

A halo (ἅλως; also known as a nimbus, icebow or Gloriole) is an optical phenomenon that appears near or around the Sun or Moon, and sometimes near other strong light sources such as street lights. There are many types of optical halos, but they are mostly caused by ice crystals in cold cirrus clouds located high (5–10 km, or 3–6 miles) in the upper troposphere. The particular shape and orientation of the crystals is responsible for the type of halo observed. Light is reflected and refracted by the ice crystals and may split up into colors because of dispersion, similarly to the rainbow.

Sometimes in very cold weather optical halos are formed by crystals close to ground level, called diamond dust. The crystals behave like jewels, refracting and reflecting sunlight between their faces, sending shafts of light in particular directions.

Atmospheric phenomena such as halos were used as an empirical means of weather forecasting before meteorology was developed.

Other common optical phenomena involving water droplets rather than ice crystals include the glory and the rainbow.

Light pillar

Sun pillar near Harpers Ferry, West Virginia.

Main article: Light pillar

A light pillar, or sun pillar, appears as a vertical pillar or column of light rising from the sun near sunset or sunrise, though it can appear below the sun, particularly if the observer is at a high elevation or altitude. Hexagonal plate- and column-shaped ice crystals cause the phenomenon. Plate crystals generally cause pillars only when the sun is within 6 degrees of the horizon, or below it; column crystals can cause a pillar when the sun is as high as 20 degrees above the horizon. The crystals tend to orient themselves near-horizontally as they fall or float through the air, and the width and visibility of a sun pillar depends on crystal alignment.

Light pillars can also form around the moon, and around street lights or other bright lights. Pillars forming from ground-based light sources may appear much taller than those associated with the sun or moon. Since the observer is closer to the light source, crystal orientation matters less in the formation of these pillars.

Icebow

22 degrees halo around the Moon

Icebow over the Kluane Range viewed from the Alaska Highway

An icebow is phenomenon similar to a rainbow except that it is formed by the refraction of sunlight through cloud suspended ice crystals as opposed to raindrops or other liquid water suspended in the air. Generally the appearance is as arc sections as opposed to a full circle. Brighter sections usually occur above, below, and lateral to the center (where the sun is visible). These bright areas are referred to as "sun dogs," "parhelia" (plural), or mock suns because of their bright appearance and possible confusion with the actual location of the sun. Those icebows that are caused by very small ice crystals are one colour, because diffraction blurs the colours together. A 22 degree icebow has red on the inside and blue on the outside.

A diffraction disc or Airy disc has similar appearance, but is a disk, rather than a ring, and has a red border on the inside. Its size depends on the size of the ice or water particles that cause it. These are also known as coronas, but are not to be confused with the thin streaming luminous gas that makes up the sun's own corona.

A noontime Halo that was visible in Tacoma, WA, on June 19th, 2007	Halo and sundog with a brilliant larger arc	Image:Solar-halo.jpg	Subsun
Complex halo display at South Pole	Complex Moon halo. You could see Halo, Parry arc,upper tangent arc and Moon dogs