- 記錄人類文明的那些美文（環(huán)球時代美文讀本）
- 吳中東 宮玉波
- 864字
- 2020-08-20 09:57:23
10 Meteorology
海洋大氣科學(xué)：介紹大氣與海洋之間的交界面上產(chǎn)生湍流的研究
導(dǎo)讀
湍流是流體的一種流動狀態(tài)。當流速很小時，流體分層流動，互不混合，稱為層流，也稱為穩(wěn)流或片流；逐漸增加流速，流體的流線開始出現(xiàn)波浪狀的擺動，擺動的頻率及振幅隨流速的增加而增加，此種流況稱為過渡流；當流速增加到很大時，流線不再清楚可辨，流場中有許多小漩渦，層流被破壞，相鄰流層間不但有滑動，還有混合。這時的流體作不規(guī)則運動，有垂直于流管軸線方向的分速度產(chǎn)生，這種運動稱為湍流，又稱為亂流、擾流或紊流。
本文主要介紹大氣與海洋之間的交界面上產(chǎn)生湍流的現(xiàn)象。
The transfer of heat and water vapor from the ocean to the air above it depends on a disequilibrium at the interface
of the water and the air. Within about a millimeter of the water, air temperature is close to that of the surface water, and the air is nearly saturated with water vapor. But the differences, however small, are crucial, and the disequilibrium is maintained by air near the surface mixing with air higher up, which is typically appreciably cooler and lower in water-vapor content. The air is mixed by means of turbulence that depends on the wind for its energy. As wind speed increases, so does turbulence, and thus the rate of heat and moisture transfer. Detailed understanding of this phenomenon awaits further study. An inter-acting—and complicating—phenomenon is wind-to-water transfer of momentum that occurs when waves are formed. When the wind makes waves, it transfers important amounts of energy—energy that is therefore not available to provide turbulence.
熱量和水蒸氣從海洋向海面上的空氣傳輸取決于水與空氣之間分界面上的一種不平衡現(xiàn)象。離水面大約一毫米的距離內(nèi)，空氣的溫度接近水面溫度，空氣中的水蒸氣接近飽和。但是其間的差別不管多么微小，卻是極其重要的；這種不平衡現(xiàn)象是由同較高處空氣混合的接近海面的空氣來保持的。可以感覺到這樣的特點：較高處的空氣比接近海面的空氣氣溫低，水蒸氣含量低。空氣的混合取決于由風(fēng)掀起的湍流。風(fēng)速增加，湍流也隨之增加，因而熱量和水蒸氣的傳輸速度也隨之增加。對于這種現(xiàn)象的詳盡理解有待于進一步研究。因為當波浪形成時，風(fēng)向海水傳輸動量是一種相互作用的復(fù)雜現(xiàn)象。風(fēng)掀起波浪時，向海水傳輸大量能量——因而這種能量不可能用來產(chǎn)生湍流。
Sentence Translation
句子翻譯
1. But the differences, however small, are crucial, and the disequilibrium is maintained by air near the surface mixing with air higher up, which is typically appreciably cooler and lower in water-vapor content.
2. An interacting—and complicating—phenomenon is wind-to-water transfer of momentum that occurs when waves are formed.
Key
1．但是其間的差別不管多么微小，卻是極其重要的；這種不平衡現(xiàn)象是由同較高處空氣混合的接近海面的空氣來保持的。
2．因為當波浪形成時，風(fēng)向海水傳輸動量是一種相互作用的復(fù)雜現(xiàn)象。