Shiranui (optical phenomenon)

Shiranui (不知火, unknown fire, Shiranuhi in the historical kana orthography) is an atmospheric ghost light told about in Kyushu.

These will split off to the left and right and multiply, eventually producing anywhere from several hundred to several thousand flames in a row.

Sometime the light is a large ball of fire rising from the surface of the sea to a height of 60 feet; sometimes it is a line of pale red, fiery globes drifting and down the tide.

[6] According to one theory from the Shōwa era by Machika Miyanishi, professor of Kumamoto Higher Technical School and Hiroshima Higher Technical School, who made extensive scientific studies and wrote eight papers, including two English papers, the time when shiranui appear is the time when the temperature of the sea is the greatest in the year, and the tide would sink about 6 meters, resulting in a mudflat and sudden radiative cooling, and overlapping with the land formation at the Yatsushiro Sea and the Ariake Sea, the lights of the boats that would depart to get the fish of the tidelands would get refracted.

[2] This theory is seen as having merit even in the modern era, and Miyanishi Machika, of the high industries of Kumoto and a professor from the Hiroshima Higher Technical School, researched this as his specialty.

According to him, the shiranui are fires for luring fish at night (isaribi), their flickering and their alliance and rupture, helped with optical illusions, results in it being seen as mysterious flames.

[8] Tairi Yamashita, Professor at Kumamoto University, made extensive studies of Shiranui using modern instruments with the assistance of students.

He concluded that "Shiranui is an optical phenomenon resulting from light going through the complicated distributions of clumps of air with different temperatures and getting refracted.

[11] Tairi Yamashita, Professor at Kumamoto University, made extensive studies of Shiranui using modern instruments with the assistance of students.

[12] Nowadays, the tidal flats are all filled up, lightbulbs illuminate the darkness of the night, and the seawater has become polluted making it difficult to see these shiranui.