Footprints of My Mind

 （photos and videos by my relative, used under authorization）        A full circular rainbow appeared at Hukou Waterfall in China! A photo can't show the full circle but a video can. (Click the arrow to view the video that was uploaded to YouTube)       Opposite to the common theory that full circular rainbow cannot be seen on land/ground as the land blocks its lower half, a full circular rainbow did really appear under the blue sky beside the cliff in the mist at Hukou Waterfall in China. The time was 4 September 2026, at 4:38 p.m. in the afternoon on the Shaanxi side of Hukou Waterfall, when the sun was shining from the back of the viewer towards the waterfall.               The narrow gully in Hukou (meaning like the narrow opening of a pot) confines the river water and causes a lot of water droplets splashing up, which create a mist above the waterfall, providing a backdrop for rainbows and even rainbow ...

(English summary at the bottom of this article. Translation function in the sidebar. Photos and videos used under authorization.  照片和錄像由原來拍攝者授權使用) 壺口瀑布出現在陸地上罕見的圓環形彩虹 circular rainbow or rainbow circle seen at Hukou Waterfall in China                 九月初，繼日前甘泉大峽谷和波浪谷之旅，親友再傳來位於山西省臨汾市吉縣與陝西省延安市宜川縣交界的‘千里黃河一壺收’ - 壼口瀑布的照片及錄像（在陜西宜川的壺口瀑布觀景區拍攝的，而不是到山西那邊的壺口瀑布觀景區），其中竟然有圓環形的彩虹，蔚為奇觀！照片不能盡錄，只有用 錄像拍攝圓環形的彩虹。        還以為網上有關壺口瀑布會有很多類似的環形彩虹錄像，但出乎意料，在Youtube未有發現！點擊箭頭，便可打開只有六秒的短片，看到陸地上罕見的環形彩虹了：        也許有人在壺口瀑布見過環形彩虹，但拍攝它並不容易，看過錄像可能會明白有多麼困難：        環形彩虹的形成，是因為瀑布水花噴發出來所形成的水霧，像舞台的背景佈幕，當陽光照射水霧，如果我們站在適當位置和用適當角度觀看，便會看到完完整整的圓環形彩虹！        如錄像/照片所見，當拍攝者拿著鏡頭向着水霧拍攝（水霧可能亦要夠多、夠高、範圍夠大），水點正不斷打向人和鏡頭，因此拍攝過程中，要忍受水花曬面和全身濕透，亦需不停抹乾鏡頭，穩定地舉高手‘高抄’（從高位向下拍攝）。 以下是發現環形彩虹的前奏 - 四份三個彩虹在崖邊：        和親友詳談，憶述發現環形彩虹的經過，如上一段錄像所見，他是因為先看見有3/4的彩虹，便推測可能會有完整的環形彩虹，於是在現場不斷調整自己的位置去觀察水霧。 最終，皇天不負有心人，他終於在某位...

 English Summary        Special geological factors cause spectacular scenery at a gully called Longbagou Valley (龍巴溝) in Shaanxi, China.         As the photos illustrate, historic sedimentary rock layers are cracked into gullies during earthquakes, walls are twisted, which look like dancing.         The wide range of colors are caused by various factors : sunlight angle, blue light in the sunlight, moss, weather, viewing angle, timing and season of viewing, degree of sunshine, etc.       親友傳來第三批景點的照片，是 龍巴溝 (九月初早上十時許入溝）。        照片像萬花筒的圖案，沒有直線，只有曲線，堅硬的岩層好像扭毛巾一般被扭曲了，似哈哈鏡，有點狂野。         稍為查看網上有關 龍巴溝 的介紹，見不少人都施展渾身解數去描繪，例如‘瘋狂的石頭’、‘崖壁年輪’（參考資料1）、‘魔幻的地下天堂’（資料2）、‘時空隧道’（資料3）、狹長幽深，九曲迴轉（資料4）等。         到 龍巴溝 一行，文學家會發揮無限想像創意；探險家會探索奇幻撲索迷離之境。至於我，肯定頭暈眼花，天旋地轉，且看看照片！ 如走入地心的旋渦， 如進入地心探險般        所有照片是用手機的自動模式拍攝的，不是人手調校的，光線是天然陽光，沒有人造光。上圖明顯...

(中文在英文下面) English Summary        The following recorded a trip to a red sandstone gorge and valley formed at least 60 million years ago, the Bolang Valley (Bolanggu) in Shaanxi, northern China, which is an example of Danxia landform / topography.        The spectacular and large scale wavy red sandstone rock layers looks like waves in the sea and the landscape of The Moon or Mars.       There are narrow slit gullies, swamp wetland, river, cliffs, and rocks with strange shapes like animals lying on the ground. The wave patterns might be caused by water and wind erosion as well as  earthquake movements.        The famous slit gully here in BolangValley, which is very narrow, is nicknamed 'A streak of sky' or 'Heaven's gap' (一綫天). It was due to an earthquake that split up the rock layers. The experience of walking inside was like going to the center of the Earth, with twists and turns that seem like leading to ...