1:45 PM - 3:15 PM
[O11-P46] The long-awaited observation success! Unraveling the true nature of the mysterious phenomenon "Shiranui"
Keywords:mirage, refraction, observation, tide, simulation, optics
This is the seventh year that I have been studying Shiranui. In the past six years, I have made 23 field observations of shiranui, but they have never appeared. This year's research was based on the following three questions: 1. what kind of phenomenon is shiranui? 2. what is the principle of the observed shiranui? 3. why was shiranui seen?
Question 1: What phenomenon is shiranui? According to literature, Shiranui is a mysterious phenomenon of light seen in the Shiranui Sea on the eve of Hassaku (the first day of the eighth lunar month), and is now considered a type of mirage. In order to make the Shiranui observation a success, we interviewed local people about Shiranui and found out that the reason why Shiranui was not seen in the past six years was the lack of fishing fires. Therefore, they put out a fishing fire and conducted field observations, and succeeded in observing Shiranui for the first time in 36 years and capturing a clear moving image for the first time in the world.
Question 2: What is the principle of the observed shiranui? Shiranui is considered a type of mirage. Lower mirages, which are common mirages, occur in the upper-cooled and lower-warmed air layers, and the scenery changes in the vertical direction. Based on the generation principle of this mirage, we considered that a shiranui occurs when there are innumerable lateral temperature differences on the sea surface. This principle of shiranui occurrence coincided with the conditions under which shiranui occurred, which we succeeded in reproducing last year. Therefore, we considered that shiranui is generated by temperature differences in the lateral direction.
Question 3: Why were shiranui seen? Because fishing fires are lights from ships, they are closer to the sea surface than street lights and other town lights. Therefore, we conducted a light path simulation of the mirage by focusing on the height of the light source from the sea surface. As a result, we found that when the light source is a streetlight, the mirage is not visible at the viewing site where the shiranui is seen, whereas the mirage is visible when the fishing fire is seen. Therefore, it is thought that the reason why Shiranui was seen this year was because the light source was a fishing fire.
From the observation of Shiranui after 36 years, it was found that a fishing fire is necessary to observe Shiranui in the present day. We also found that the principle of shiranui occurrence is the difference in temperature in the lateral direction. In the future, we will elucidate why shiranui occur only during a limited period of time, namely, Hassaku.
Question 1: What phenomenon is shiranui? According to literature, Shiranui is a mysterious phenomenon of light seen in the Shiranui Sea on the eve of Hassaku (the first day of the eighth lunar month), and is now considered a type of mirage. In order to make the Shiranui observation a success, we interviewed local people about Shiranui and found out that the reason why Shiranui was not seen in the past six years was the lack of fishing fires. Therefore, they put out a fishing fire and conducted field observations, and succeeded in observing Shiranui for the first time in 36 years and capturing a clear moving image for the first time in the world.
Question 2: What is the principle of the observed shiranui? Shiranui is considered a type of mirage. Lower mirages, which are common mirages, occur in the upper-cooled and lower-warmed air layers, and the scenery changes in the vertical direction. Based on the generation principle of this mirage, we considered that a shiranui occurs when there are innumerable lateral temperature differences on the sea surface. This principle of shiranui occurrence coincided with the conditions under which shiranui occurred, which we succeeded in reproducing last year. Therefore, we considered that shiranui is generated by temperature differences in the lateral direction.
Question 3: Why were shiranui seen? Because fishing fires are lights from ships, they are closer to the sea surface than street lights and other town lights. Therefore, we conducted a light path simulation of the mirage by focusing on the height of the light source from the sea surface. As a result, we found that when the light source is a streetlight, the mirage is not visible at the viewing site where the shiranui is seen, whereas the mirage is visible when the fishing fire is seen. Therefore, it is thought that the reason why Shiranui was seen this year was because the light source was a fishing fire.
From the observation of Shiranui after 36 years, it was found that a fishing fire is necessary to observe Shiranui in the present day. We also found that the principle of shiranui occurrence is the difference in temperature in the lateral direction. In the future, we will elucidate why shiranui occur only during a limited period of time, namely, Hassaku.