〈石鎚神社中宮成就社境内より霧氷咲く石鎚山頂を望む〉 The ice rime-covered summit of Mt. Ishizuchi, viewed from the precincts of Chugu Jojusha of Ishizuchi Shrine
2022年1月、西日本最高峰石鎚山（標高1982㍍）の7合目、成就地区（1450㍍）に新春がやって来た、といっても季節は冬。近年降雪量は確実に減っているが、これも地球温暖化の影響か？30年～40年前の1月中旬なら成就社境内に積雪1㍍を越えることも珍しくはなかったが、本日1月13日の積雪は20㌢程。2月中旬の最も降雪のある時期でさえ積雪数センチということもある。
しかしながら、気温に関しては以前と変わらず寒いと氷点下15度まで下がる。暖かいと希に2度3度、あるいはそれ以上になる日もあるが、平均すると氷点下となりその5度前後を温度計は指している。
そんな環境のなか、自然はそこを訪ねる人々に時として冒頭の画像のような凛とした澄んだ麗しの光景を展開してくれる。氷花がキラキラと陽に煌めくダイヤモンドダストだってここ南国四国で観ることができるのだ・・・。
～今回は、皆さんも実際に観たりされてもいるでしょう石鎚山の「霧氷」等についてご紹介させて頂きます。霧氷は、過冷却された霧粒が風で木などに吹き付けられ、その刺激で氷となって付いたもので、風上に向かって延びていき透明感があり固くなります。よく似たものに「樹氷」がありますが、厳密には区別され全体に白く見え、空気を多く含んでいるので脆く、樹木が完全に覆われてしまうこともあります。
〈有名な蔵王の樹氷/スノーモンスターなどとも呼ばれる〉 Famous Tree frost "Jyuhyo" in Zao; often labelled as "Snow Monsters"
〈成就地区で観る霧氷〉Rime ice "Muhyo" found in Joju area
次に「雨氷」についてですが、この言葉自体初めて耳にする方もいらっしゃるかと思います。取り敢えず画像をご覧下さい。いずれも過年に成就社境内で撮ったもので、なかなかお目にかかれません。
・・・どうでしょう？この現象は、氷点下になっても凍っていない過冷却状態の雨が地面の物や木々について、氷でコーティングされた状態になっています。
では、もう一つご紹介。「樹霜」です。これもあまり聞き覚えがない単語かと思いますが、とある日の成就社殿シメナワの画像をご覧頂きましょう。これまた珍しく・・・。
樹霜は、水蒸気が気温の低下で昇華し、地面より高いところの木々や物にできる霜のことですが、ご覧の通り四方八方に成長して方向性はありません。
その他に「粗氷」という現象もあって、今回の画像でいうと「雨氷」に近く木々や物を氷でコーティングした状態になります。雨氷は雨が凍り付くので「つらら」の様な雫状の氷も観られますが、粗氷は霧などが凍り付くので雫氷は生まれません。
・・・で大きい声では言えませんが・・・・・、今回ご紹介させて頂いた「○氷」ですが・・・・・・・・・・・・・ひっくるめていうと・・・・・すべて・・・・・・「霧氷」になります！！
(^^;) ﾊﾊﾊ・・・しかも・・・ｺﾎﾝ・・・知らなくても別段困りません(^_^)v
あっ、「つらら／氷柱」も出ましたので、氷纏め？として最後に成就社境内某所の巨大つらら画像をUPします。大きいものは長さ2㍍以上もありましたとさ(^^)/
・・・今は、季節柄静なる時に日を送る石鎚山ですが、大自然は本格的な春の到来を目指して、それぞれにその準備を進めています。石鎚山開山一千三百数十年、変わらない営みが今日も続いています。
令和4年1月13日投稿
石鎚神社 祢宜 曽我部英司／NPO法人石鎚森の学校事務局長 リチャード
Richard's Column "It doesn't bother you even if you don't know it, but..." vol. 4
"Ice, ice, ice, and ice...?"
It's January, 2022, we welcomed New Year here in Joju area (located at an elevation of 1,450 meters) , which is at the seventh station of Mt. Ishizuchi, the highest peak in western Japan (at an elevation of 1,982 meters). In Japanese, we often use the word "Early Spring" (Hatsu-haru, or Shin-shun) to celebrate the coming of New Year, but we are still in the midst of winter. In recent years, the amount of snowfalls is getting smaller and smaller, which I think reflects another influence of the climate change. Thirty to forty years ago, it was not at all unusual that the precincts of Jojusha Shrine was covered in more than one metre of snow in mid-January, but today (13, January 2022), we have only 20 centimeters of snow. These days, even in mid-February, when we should have the largest snowfalls, we have only 5-6 centimeters of snow.
When it comes to temperature, however, we still have a very cold winter and it comes to sub-zero temperature; it comes down to minus 15 degrees celsius on a cold day. Very rarely we have a warm day and it's 2 or 3 degrees or warmer, but the average temperature of Joju area in winter falls below the freezing point; we usually find our thermometer showing minus 5 degrees.
Thus, our great Nature shows the visitors so impressive a sight like the picture above; the ice rime-covered summit shining against the clear blue sky is so dignified and breath-takingly beautiful. Shikoku island, whose highest peak is Mt. Ishizuchi, is located to the southwest of the main island, so people call Shikoku a warm Southland, but once you come up to the seventh station of the mountain, you can see diamond dust composed of tiny ice crystals, often called "Ice Flowers" shining brightly in the sun...
Today, let me talk about such a beautiful "Rime ice" called Muhyo (literally meaning "Fog-ice") in Japanese of Mt. Ishizuchi. Rime ice is formed when small supercooled water droplets freeze onto surfaces. The fog freezes usually to the windward side of tree branches, and gets clear and solid. The phenomenon called "Tree frost" called Juhyo (literally meaning "Tree-ice") in Japanese looks similar, but to be strict, Rime ice and Tree frost should be distinguished; Tree frost looks whiter and fragile, and it often covers not only branches but the whole trees; fully-covered trees look like white monsters and that is why the well-known frost covered trees in Zao are called "Snow Monsters".
Well, let me move on to the phenomenon called "Glaze ice" called Uhyo (literally meaning "Rain-ice") in Japanese. Many of you have never heard of this name before. Please have a look at the pictures below. These pictures were taken in the precincts of Jojusha Shrine a couple of years ago, and I should say they are very, very rare pictures.
...how do you like them? "Glaze ice" phenomenon occurs when the supercooled rain drops, which have not frozen yet even at the temperature below zero, freeze upon impact with cold surfaces of grounds or trees and are coated by ice.
Then, let me give you one more phenomenon; it's "Air Hoar" called Jyuso (literally meaning "Tree-hoar"). Again, the term sounds quite strange to many of you, so let me show you the pictures of Shimenawa rope, a sacred rice straw festoon, of Jojusha Shirine. Again, they are very rare pictures...
"Air Hoar" is deposit of hoar frost on objects above the surface, such as tree branches and, as you see in these pictures, it grows in any directions, both vertically and horizontally.
Besides, we have another phenomenon called "Hard rime" called Sohyo (literally meaning "Coarse ice"), which is somehow similar to "Glaze ice" above and again "Hard rime" appears in the form of ice coating branches and other objects. While "Glaze ice" is frozen rain, thus it often appears in the form of drops like icicles, "Hard rime" is formed by water droplets in fog freezing to the outer surfaces of objects, thus does not appear in the form of icicles.
...well, I hope it does not upset you, but all the phenomena that I have explained so far, I mean "Muhyo", "Juhyo", "Uhyo" and "Sohyo"...I know they look somehow similar and my explanation must have sounded quite complicating, I know.........To be very honest, however, they all belong to the same phenomenon....well, I mean they are all "Rime ice"! Ha-ha-ha...and again...ahem!...it does not bother you even if you don't know it, but it might make your life a bit happier, as I always say at the opening and ending of my columns, you know ;-D
Oh, talking about icicles, let me show you the picture of the huge icicles taken at somewhere in the precincts of Joju shrine. One of the largest one was more than 2 meters long! Amazing, isn't it?
...At present, Mt. Ishizuchi is surrounded with tranquility of winter. Nevertheless, please remember that the Great Nature is quietly but surely preparing for coming of spring. Seasons come and go, that has been unchangeable Nature's work for more than 1300 years since when Mt. Ishizuchi, our sacred peak was opened.
-- Hideshi Sogabe, Senior Priest of Ishizuchi Shrine, a.k.a Richard; Director and Secretary General of NPO Ishizuchi Mori-no-Gakko “School of the Woods” (13, January 2022)