1:45 PM - 3:15 PM
[O11-P41] What are the conditions for a beautiful sunset in Hachioji City, as considered from weather and topographical maps?
Keywords:sunset, clouds, topography, Hachioji City
1. Objective
Sunsets are attractive and familiar to many people and can be a tourist resource. In order to understand the regional characteristics of sunsets, this study focused on topography and clouds in Hachioji City.
2. hypothesis
It is said that “when altocumulus clouds (sheep clouds) and cirrocumulus clouds (scaly clouds) float in the high western sky, sunlight is scattered further by cloud particles, and beautiful sunsets are likely to occur. However, in Hachioji City, the mountainous area to the west creates an updraft that forms low clouds, making it difficult to see the sunset.
3. Methodology
In summer, we photographed the sky from east to west, north to south, and south to south for 14 days near our home in Hachioji City during sunset hours to estimate the types of clouds. The weather, humidity, and weather map at 18:00 were taken as data. In order to compare the differences in topography, we also collected observation data in the vicinity of Tokyo Station and Toyohashi City, Aichi Prefecture, in the same way. A “beautiful sunset” is defined as a sunset where the sun is not obscured by clouds, or where the clouds are colored even if they are obscuring the sun.
4. Results
The following pictures are the results.
5. Discussion
First, from Figures 4, 5, 6, and 9, it is considered that mid to upper level clouds, such as altocumulus and cirrocumulus clouds, tend to be colored.
Also, from Figures 2 and 3, it can be seen that the area near Tokyo is farther from the mountains to the west than Hachioji City, and Toyohashi City in Aichi Prefecture has no mountains to the west. Observations at these two locations produced the beautiful sunsets shown in Figures 4 and 5. When these conditions were examined, the weather was clear and the humidity was about 60%. The sunset in Hachioji City under the same conditions, Figure 6, had the sun hidden by clouds. Cloud images and topographic maps of this day were additionally examined (Figure 7). It can be seen that the reddish-black areas and mountainous locations were covered with dense clouds. In other words, the clouds hiding the sunset in Figure 6 were probably formed by the topography of Hachioji City.
Beautiful sunsets could also be seen in the northern and southern skies (Figure 9). On this occasion, as shown in Figure 8, the weather map shows that the observation location (Hachioji City) was under high pressure and thus clear, but the inflow of water vapor due to an approaching low pressure system and frontal system was thought to have produced clouds that easily colored the sky, resulting in a beautiful sunset.
6. Issues
The issue is to clarify the basis for the occurrence of clouds in mountainous areas. In addition, we would like to set up a fixed-point camera for long-term observation.
Acknowledgments
I would like to thank Professor Yoshihiro Iijima of the Faculty of Urban Environment, Tokyo Metropolitan University, the staff at the Japan Meteorological Agency's Weather Science Museum, a friend living in Toyohashi City, Aichi Prefecture, teachers at Tokyo Metropolitan Hachioji Higashi High School, and others who helped us with this project.
References
“GSI Website” https://maps.gsi.go.jp/#5/36.104611/140.084556/&base=std&ls=std&disp=1&vs=c1g1j0h0k0l0u0t0z0r0s0m0f1,2025.1.18
”Weather News Weather Forecast” https://weathernews.jp/, 2024.7.22 - 2024.8.5
”JMA Weather Maps” https://www.jma.go.jp/bosai/weather_map/, 2024.7.22 - 2024.8.5
”JAXA Himawari Monitor Cross-cutting Product Provisioning System (P-Tree)” https://www.eorc.jaxa.jp/ptree/index_j.html, 2025.1.18
”Why do we see the sky in magical colors? The mystery of twilight and magic hour | Honda Kids (Kids) | Honda official website” https://www.honda.co.jp/kids/explore/twilight/,2024.11.9
Mai Kikuchi, “Tokimeku Kumo Zukan” (The Illustrated Book of Exciting Clouds), Yama-kei Publishers, 2020.
Kentaro Araki, “Saiko ni Sugosugiru Tenki no Zukan” (Illustrated Book of The Most Amazing Weather) KADOKAWA,2024
Sunsets are attractive and familiar to many people and can be a tourist resource. In order to understand the regional characteristics of sunsets, this study focused on topography and clouds in Hachioji City.
2. hypothesis
It is said that “when altocumulus clouds (sheep clouds) and cirrocumulus clouds (scaly clouds) float in the high western sky, sunlight is scattered further by cloud particles, and beautiful sunsets are likely to occur. However, in Hachioji City, the mountainous area to the west creates an updraft that forms low clouds, making it difficult to see the sunset.
3. Methodology
In summer, we photographed the sky from east to west, north to south, and south to south for 14 days near our home in Hachioji City during sunset hours to estimate the types of clouds. The weather, humidity, and weather map at 18:00 were taken as data. In order to compare the differences in topography, we also collected observation data in the vicinity of Tokyo Station and Toyohashi City, Aichi Prefecture, in the same way. A “beautiful sunset” is defined as a sunset where the sun is not obscured by clouds, or where the clouds are colored even if they are obscuring the sun.
4. Results
The following pictures are the results.
5. Discussion
First, from Figures 4, 5, 6, and 9, it is considered that mid to upper level clouds, such as altocumulus and cirrocumulus clouds, tend to be colored.
Also, from Figures 2 and 3, it can be seen that the area near Tokyo is farther from the mountains to the west than Hachioji City, and Toyohashi City in Aichi Prefecture has no mountains to the west. Observations at these two locations produced the beautiful sunsets shown in Figures 4 and 5. When these conditions were examined, the weather was clear and the humidity was about 60%. The sunset in Hachioji City under the same conditions, Figure 6, had the sun hidden by clouds. Cloud images and topographic maps of this day were additionally examined (Figure 7). It can be seen that the reddish-black areas and mountainous locations were covered with dense clouds. In other words, the clouds hiding the sunset in Figure 6 were probably formed by the topography of Hachioji City.
Beautiful sunsets could also be seen in the northern and southern skies (Figure 9). On this occasion, as shown in Figure 8, the weather map shows that the observation location (Hachioji City) was under high pressure and thus clear, but the inflow of water vapor due to an approaching low pressure system and frontal system was thought to have produced clouds that easily colored the sky, resulting in a beautiful sunset.
6. Issues
The issue is to clarify the basis for the occurrence of clouds in mountainous areas. In addition, we would like to set up a fixed-point camera for long-term observation.
Acknowledgments
I would like to thank Professor Yoshihiro Iijima of the Faculty of Urban Environment, Tokyo Metropolitan University, the staff at the Japan Meteorological Agency's Weather Science Museum, a friend living in Toyohashi City, Aichi Prefecture, teachers at Tokyo Metropolitan Hachioji Higashi High School, and others who helped us with this project.
References
“GSI Website” https://maps.gsi.go.jp/#5/36.104611/140.084556/&base=std&ls=std&disp=1&vs=c1g1j0h0k0l0u0t0z0r0s0m0f1,2025.1.18
”Weather News Weather Forecast” https://weathernews.jp/, 2024.7.22 - 2024.8.5
”JMA Weather Maps” https://www.jma.go.jp/bosai/weather_map/, 2024.7.22 - 2024.8.5
”JAXA Himawari Monitor Cross-cutting Product Provisioning System (P-Tree)” https://www.eorc.jaxa.jp/ptree/index_j.html, 2025.1.18
”Why do we see the sky in magical colors? The mystery of twilight and magic hour | Honda Kids (Kids) | Honda official website” https://www.honda.co.jp/kids/explore/twilight/,2024.11.9
Mai Kikuchi, “Tokimeku Kumo Zukan” (The Illustrated Book of Exciting Clouds), Yama-kei Publishers, 2020.
Kentaro Araki, “Saiko ni Sugosugiru Tenki no Zukan” (Illustrated Book of The Most Amazing Weather) KADOKAWA,2024