Ulloa's Halo - Meteorological phenomenon
Illustration from the Chapter L´Atmosphère
Camille Flammarion, Météorologie populaire, 1888.
Ulloa is the namesake for the meteorological term "Ulloa's halo" (also known as "Bouguer's halo"), which an observer may see infrequently in fog when the sun breaks through (for example, on a mountain) — effectively a "fog-bow" (as opposed to a "rain-bow"). A fog-bow is defined as "an infrequently observed meteorological phenomenon; a faint white, circular arc or complete ring of light that has a radius of 39 degrees and is centered on the antisolar point. When observed, it is usually in the form of a separate outer ring around an anticorona."
Antonio de Ulloa y de la Torre-Giral, FRS, FRSA, KOS (12 January 1716 – 3 July 1795) was a Spanish general of the navy, explorer, scientist, author, astronomer, colonial administrator and the first Spanish governor of Louisiana. He was appointed to that office after France ceded the territory to Spain in 1763.
Ulloa had already established an international reputation in science, having been part of the French Geodesic Mission in present-day Ecuador. He published an extensive record of his observations and findings on the South American trip, which was published in French in 1848 and in English as A Voyage to South America (1806). He was a Fellow of the Royal Society and a foreign member of the Royal Swedish Academy of Sciences.
Cloudbow, from the Chapter L´Atmosphère
Camille Flammarion, Météorologie populaire, 1888.
From the top of the Pambarmarca mountain, a strange weather phenomenon was noticed by Don Antonio de Ulloa and several other climbers who had gone there to establish signal posts for surveys. As the cloud covered hills became clear of the clouds and frost with the Sun rising, each person on the hill top started noticing his own image at distance of about 10 miles opposite to the Sun. In this image, the head of each one of them appeared (individually) within the centre of three concentric irises (with colours coalescing with each other) as if each one, individually, was seeing his mirror image; these were perpendicular to the horizon. An arch in white colour was seen at a distance from the three irises, circumscribing them. The diameter of the central iris was initially measured as 5.5 degrees while the arch around the circles was 57 degrees in size. Initially, the arches were seen in oval shape and as the Sun rose above the horizon it changed to a perfect circular shape, like the disc of the Sun. The arches displayed red colour bordered by orange colour, followed by bright yellow becoming straw colour and finally into green. However, the outer arch was seen all through in red colour only. Similar arches were seen when the Moon was rising. Such a phenomenon was noticed by the survey team frequently on the mountains here. In the past, others had also observed this phenomenon and named it as the "frostbow" or "cloudbow" as the cloud vaporized with sun rise. They are also called it the White rainbows unlike the rainbows which formed after rains.
Nicolas Camille Flammarion FRAS (26 February 1842 – 3 June 1925) was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction novels, and works on psychical research and related topics. He also published the magazine L' Astronomie, starting in 1882. He maintained a private observatory at Juvisy-sur-Orge, France.
Ulloa's Halo - Meteorological phenomenon
Illustration from the Chapter L´Atmosphère
Camille Flammarion, Météorologie populaire, 1888.
Ulloa is the namesake for the meteorological term "Ulloa's halo" (also known as "Bouguer's halo"), which an observer may see infrequently in fog when the sun breaks through (for example, on a mountain) — effectively a "fog-bow" (as opposed to a "rain-bow"). A fog-bow is defined as "an infrequently observed meteorological phenomenon; a faint white, circular arc or complete ring of light that has a radius of 39 degrees and is centered on the antisolar point. When observed, it is usually in the form of a separate outer ring around an anticorona."
Antonio de Ulloa y de la Torre-Giral, FRS, FRSA, KOS (12 January 1716 – 3 July 1795) was a Spanish general of the navy, explorer, scientist, author, astronomer, colonial administrator and the first Spanish governor of Louisiana. He was appointed to that office after France ceded the territory to Spain in 1763.
Ulloa had already established an international reputation in science, having been part of the French Geodesic Mission in present-day Ecuador. He published an extensive record of his observations and findings on the South American trip, which was published in French in 1848 and in English as A Voyage to South America (1806). He was a Fellow of the Royal Society and a foreign member of the Royal Swedish Academy of Sciences.
Cloudbow, from the Chapter L´Atmosphère
Camille Flammarion, Météorologie populaire, 1888.
From the top of the Pambarmarca mountain, a strange weather phenomenon was noticed by Don Antonio de Ulloa and several other climbers who had gone there to establish signal posts for surveys. As the cloud covered hills became clear of the clouds and frost with the Sun rising, each person on the hill top started noticing his own image at distance of about 10 miles opposite to the Sun. In this image, the head of each one of them appeared (individually) within the centre of three concentric irises (with colours coalescing with each other) as if each one, individually, was seeing his mirror image; these were perpendicular to the horizon. An arch in white colour was seen at a distance from the three irises, circumscribing them. The diameter of the central iris was initially measured as 5.5 degrees while the arch around the circles was 57 degrees in size. Initially, the arches were seen in oval shape and as the Sun rose above the horizon it changed to a perfect circular shape, like the disc of the Sun. The arches displayed red colour bordered by orange colour, followed by bright yellow becoming straw colour and finally into green. However, the outer arch was seen all through in red colour only. Similar arches were seen when the Moon was rising. Such a phenomenon was noticed by the survey team frequently on the mountains here. In the past, others had also observed this phenomenon and named it as the "frostbow" or "cloudbow" as the cloud vaporized with sun rise. They are also called it the White rainbows unlike the rainbows which formed after rains.
Nicolas Camille Flammarion FRAS (26 February 1842 – 3 June 1925) was a French astronomer and author. He was a prolific author of more than fifty titles, including popular science works about astronomy, several notable early science fiction novels, and works on psychical research and related topics. He also published the magazine L' Astronomie, starting in 1882. He maintained a private observatory at Juvisy-sur-Orge, France.