Did you know it was actually a "thunderbolt" path!? The surprising meteorological history hidden in the familiar famous peak, Mt. Tsukuba

The summit of Mt. Nantai, where the remains of the Mt. Tsukuba observatory are found.

It was Prince Yamashina Kikumaro who conceived the idea of building an observatory near the summit of Mt. Tsukuba and conducting meteorological observations.^*。

During the Meiji era, when Japan aimed for modernization by adopting Western civilization, Prince Yamashina Kikumaro, a member of the imperial family, studied at the German Naval Academy at the age of 17 in 1889. While staying in the city of Kiel, he became interested in meteorology.

In 1894, at the age of 22, he graduated from the German Naval Academy and returned to Japan. He served on the warship "Yoshino" during the First Sino-Japanese War, which began in the same year. After the war, he approached the Central Meteorological Observatory at the time to implement the meteorological studies he had learned during his studies in Germany, particularly high-altitude weather observation.

After hearing from Itaru Nonaka, who was conducting meteorological observations with his wife on Mt. Fuji at the time, and investigating the reality of high-altitude meteorology in mountainous areas, candidate locations for observatory construction were presented by the Central Meteorological Observatory in Mt. Tsukuba, Ibaraki Prefecture, Shimizu, Shizuoka Prefecture, and Sagamihara, Kanagawa Prefecture. Among these, Mt. Tsukuba was chosen. On January 1, 1902 (Meiji 35), the "Prince Yamashina Mt. Tsukuba Observatory" began high-altitude meteorological observations.

The observatories were located at three sites: the summit of Mt. Nantai, the mountainside, and the foothills. The summit observatory was equipped with a "single-story wooden building measuring three by six bays, with one lightning rod," and for observation equipment, it had two anemometers "capable of withstanding wind speeds of 120 meters per second." Regarding the plan to "withstand storms of over 100 meters," it is said that Prince Yamashina Kikumaro, upon hearing that the construction engineer of the time said, "Isn't that an unnecessary worry?" did not yield his own opinion, stating, "There have been storms at sea exceeding 80 meters."

Then, on September 28 of the same year, when observations began, Mt. Tsukuba was directly hit by a typhoon, and a wind speed of 72.1 m/s was recorded. The plan was correct. This maximum wind speed on Mt. Tsukuba was the highest in Japan until April 5, 1942 (Showa 17), when a wind speed of 72.5 m/s was recorded on Mt. Fuji.

When Prince Yamashina Kikumaro died in 1908 at the age of 36, the "Prince Yamashina Mt. Tsukuba Observatory" was donated to the Central Meteorological Observatory in 1909 and renamed the "Mt. Tsukuba Observatory, Affiliated with the Central Meteorological Observatory." In 1929, the observatory was rebuilt with reinforced concrete, and a commemorative photo from its completion remains. The current observatory^**The gateposts that have endured wind and snow, and the windows on the front behind them, retain the appearance of that era.

Incidentally, in addition to the observatory building on the summit of Mt. Nantai, as a memorial to Prince Yamashina Kikumaro, a wind speed meter modified from a British Baily-type anemometer remains at the entrance to the Mt. Nantai course from Mt. Tsukuba Shrine.

A "storm chaser" born and raised in a lightning path.

As soon as the rainy season ends, the summer mountain season begins. Cumulonimbus clouds (towering clouds) form as if completely covering Mt. Tsukuba, and a single bolt of lightning is emitted from them. Yes, summer mountains are also a season for dangerous lightning.

Among the various storms that occur, "the most frightening is unpredictable lightning," says Yutaka Aoki, a storm chaser photographer who continues to chase "storms." A storm chaser literally translates to "one who chases storms." On the vast North American continent, "storm chasers" equipped with observation and photography equipment on top of their vehicles became widely known through the movie "Twister." However, the origin is said to be Dr. Tetsuya Fujita, a meteorologist who proposed the "F-scale," an international standard for tornado intensity. (Yutaka Aoki, "Storm Chaser," p. 8, 2015, Yui Edit).

Yutaka Aoki was born and raised in Shimotsuma, Chikusei City, west of Mt. Tsukuba, and around 2007 (Heisei 19), he began publishing photos and videos of various storms, including cumulonimbus clouds and lightning, on the internet.

Shimotsuma, where Aoki lives, is a "lightning intersection" through which lightning generated in the Nikko mountain range and Ashio mountains in Tochigi Prefecture, and Mt. Akagi in Gunma Prefecture, passes.^*It is said that there is a shrine nearby that worships "Rai-sama" (the thunder god). Aoki, who was born and raised in Shimotsuma, says that being a "storm chaser" was his calling.

Aoki's pursuit area is within a 30km radius, from the western and southern regions of Ibaraki Prefecture to Oyama City in Tochigi Prefecture, which straddles the prefectural border.

While the "ten days after the rainy season" are characterized by continuous clear skies, the rise in temperature leads to frequent "cumulonimbus clouds" and an increase in lightning generated from them, marking the beginning of a season of intense weather phenomena.

Aoki searches for the predicted course of cumulonimbus clouds using meteorological data and pursues them by car. He positions himself outside the predicted path to avoid dangers such as lightning strikes and waits to photograph them, but predicting the course of cumulonimbus clouds is difficult. Sometimes, the cumulonimbus clouds develop into giant supercells that begin to rotate, or he encounters downbursts with strong downdrafts, and he finds himself unknowingly within the path of the cumulonimbus cloud and is startled.

Of course, his car is equipped with navigation, and he constantly monitors various data from weather radars, but things do not always go as planned. Therefore, to determine the course of cumulonimbus clouds and avoid danger, he deliberately narrows his pursuit range to a 30km radius in his familiar local area.

In cumulonimbus clouds, ice particles rub against each other, and the electrical discharge generated there is lightning. Lightning strikes, which can reach up to 200 million volts, are unpredictable. Aoki once experienced a lightning strike about 100 meters from his shooting location, which gave him a scare.

When the rainy season ends, temperatures rise, and white, fluffy clouds appear to cover Mt. Tsukuba, you should be cautious. If the clouds begin to break apart and you hear thunder in the distance, take shelter inside buildings such as cable car or ropeway stations, souvenir shops, or tourist information centers while you still have some time. Evacuate quickly if a cold wind starts to blow. If you are walking on a hiking trail, it is dangerous to be under trees or near rocks on the summit due to lightning strikes. Take early precautions, such as cutting your hike short and descending the mountain.

I pray for everyone's safety during the summer hiking season from Mt. Tsukuba, a mountain associated with weather.

MAP＆DATA

Elevation map

View surrounding maps on Yamato Time

Optimal number of days: Day Hike

Course time: 3 hr 31 min

Itinerary: Start point... Mt. Tsukuba Shrine Entrance bus stop... Mt. Tsukuba Shrine... Nakachaya ruins... Men'nugawa River source spring... Miyukigahara... Mt. Nantai [30 minute break]... Miyukigahara... Men'nugawa River source spring... Nakachaya ruins... Miyawaki Station... Mt. Tsukuba Shrine... Mt. Tsukuba Shrine Entrance bus stop

Total walking distance: Approximately 5,800m

Cumulative elevation difference: Upbound Approximately 778m Downstream Approximately 772m

Course constant: 16

Book Information

Storm Chaser
-Chasing Dreams and Storms

In May 2012, the Hojo district at the foot of Mt. Tsukuba was hit by a tornado. This weather disaster made me realize the terror of weather disasters that strike small areas. After encountering information disseminated by Yutaka Aoki, I published the book "Storm Chaser - Chasing Dreams and Storms."

Author	Yutaka Aoki
issue	Yui Edit (2015)
price	1,980 yen (tax included)

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