Dew - Dew

Japanese: 露 - つゆ

On clear nights, especially in the early morning, water droplets may adhere to grass, buds, and other objects, making them wet. This water is called dew. During the night, objects radiate heat and cool, and water vapor in the surrounding air condenses on their surfaces. On cloudy or windy nights, objects are less likely to cool, so dew is less likely to form. In winter, the lenses of glasses may fog up in a warm train. This is because dew forms on the cold lens surface. In cold seasons, dew that has adhered to objects may freeze in the morning chill. This is called frozen dew, and is easily mistaken for frost. Frost is a type of dew, and water vapor in the air turns directly into ice and adheres to objects without turning into dew. The amount of dew varies from place to place, but in Japan, the amount of dew is about 10 millimeters per year when converted into rainfall. In dry areas with little rainfall, dew is said to be useful for plant growth. The temperature at which water vapor in the air begins to condense and form dew is called the dew point temperature or dew point.

[Masaji Ohta and Hiroshi Matano]

literature

It has been seen in literary works from early on as an everyday natural phenomenon, but it has been written about a lot in waka poetry, and has developed into a lyric word. Depending on the time, place, and color, it has produced a variety of compound words such as "dawn dew," "morning dew," "evening dew," "upper dew," "lower dew," and "white dew." It has also been accompanied by words expressing various forms such as "put," "knot," "disappear," "scatter," and "disarray," leading to rhetorical devices such as hanging words and related words. It is often likened to a "pearl" or a "jewel," and is written about as piercing a jewel with a string, such as in "Manyoshu"'s "The white pearl of dew pierces the bush clover of the deer..." (Volume 8, Fujiwara Yatsuka) and "Is the spring willow piercing the white dew with a light green thread?" (First spring, Hensho) in the "Kokinshu." The impression that dew is fleeting has been around for a long time, and in the Man'yoshu, there is a poem such as "The dew leaves in the morning and disappears by evening" (Volume 2, Kakinomoto no Hitomaro). There is also an impression that dew dyes the leaves in red, and this can be seen in the Man'yoshu and Kokinshu. In the Heian period, the idea of dew as tears was seen, and in many poems, such as "Autumn is the white dew that leaves, and the dew on my pillow that wakes me up" (Love 5) in the Kokinshu. Dew is also related to the custom of covering chrysanthemums with cotton, and on the morning of September 9, if you cover chrysanthemum flowers with cotton from the night before and wipe your skin with the cotton soaked with dew, you will cast off old age, as can be seen in "Maboroshi" in the Tale of Genji and "The Diary of Murasaki Shikibu". Although dew can also mean raindrops, "autumn dew" has become fixed as the epitome of seasonal beauty, and is impressed upon people as a scene that symbolizes impermanence and sorrow. The seasonal theme is autumn. "The world of dew is the innermost sanctum of discernment for all things" (Soin).

[Teruhiko Komachiya]

[Reference item] | Frost | Dew point temperature

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

晴れた夜とくに早朝、草や木の芽その他の地物へ水玉が付着してぬれることがある。この水を露という。夜間に地物が熱を放射して冷え、周りの空気中の水蒸気がその表面に凝結してできたものである。雲の多い夜や風の強い夜には地物の冷却がおこりにくいので、露はできにくい。冬、暖かい電車内で眼鏡のレンズが曇ることがある。これは冷たいレンズの表面に露ができるためである。寒い季節には、いったん地物に付着した露が朝の寒気で凍ることがある。これは凍露といわれ、霜と間違いやすい。霜は露の同類で、空気中の水蒸気が、露とならずに直接に氷となって地物に付着したものである。露の量は所によって異なるが、日本の測定の例では雨量に換算して1年間に約10ミリメートルである。雨量の少ない乾燥地域などでは、露の水分は植物の生育に役だつといわれる。なお、空気中の水蒸気が凝結を始めて露を結ぶ温度を露点温度または露点という。

［大田正次・股野宏志］

文学

日常的な天然現象として早くから文学作品にみられるが、とくに和歌に多く詠まれ、歌語として発展してきた。「暁(あかとき)露」「朝露」「夕露」、「上(うわ)露」「下(した)露」、「白(しら)露」など、時、場所、色などによって多様な複合語を生み、「置く」「結ぶ」「消ゆ」「散る」「乱る」など多彩な様態を表す語を伴って懸詞(かけことば)や縁語などの修辞を導き出している。「珠」「玉」に見立てられることが多く、『万葉集』の「さを鹿(しか)の萩(はぎ)に貫(ぬ)き置ける露の白珠(しらたま)…」（巻8・藤原八束(やつか)）、『古今集』の「浅緑糸よりかけて白露を玉にも貫ける春の柳か」（春上・遍昭(へんじょう)）など、玉を緒(お)で貫くという形で詠んでいる。露ははかないものという印象は早くからあり、『万葉集』には「露こそば　朝(あした)に置きて　夕へには　消ゆといへ」（巻2・柿本人麻呂(かきのもとのひとまろ)）などと詠まれている。露が紅葉(もみじ)を染めるものという印象もあり、『万葉集』『古今集』にみえる。平安時代に入ると、露を涙に見立てる趣向がみられ、『古今集』の「秋ならで置く白露は寝覚めする我が手枕(たまくら)のしづくなりけり」（恋5）など数多く詠まれている。菊の着せ綿の風習にも露がかかわり、9月9日の朝に前夜から菊の花に綿をかぶせておき、露でぬれた綿で肌をぬぐうと老いを捨てるというもので、『源氏物語』「幻」や『紫式部日記』などにみえる。露は雨滴をいう場合もあるが、「秋の露」が季節美の典型として固定するようになり、無常や悲哀を象徴する景物として印象づけされた。季題は秋。「露の世や万事の分別奥の院」（宗因(そういん)）。

［小町谷照彦］

[参照項目] | 霜 | 露点温度

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