【英语时差8,16】对火焰的分析

Fire is a chemical reaction between oxygen molecules¹ and some kind of fuel. This reaction releases the heat and light that we call fire.   You might wonder how a chemical reaction like this turns into the colorful flame you see dancing on a candle. What are flames made of?

You can think of a flame as being like a kind of tent. Heat melts the candle's waxy² fuel, and turns it into a gas. This fuel gas floats away from the wick to fill the inside of the flame's tent. Outside the tent are oxygen molecules from the air. Where these two gasses meet--at the surface of the tent--is where the fiery³ chemical reaction takes place. This is called the "combustion⁴ reaction zone" of the flame, and it glows a delicate blue color.

Sometimes, however, the fuel molecules don't burn up right away. They clump⁵ together to form particles called soot⁶, which then swirl⁷ around inside the body of the flame without actually burning. As they swirl, heat from the reaction zone can make this soot begin to glow a bright orange or yellow color.

The reaction zone at the surface of the flame's tent provides the blue color of the flame. The yellow color comes from hot soot, churning around inside.

Eventually this soot will probably enter the reaction zone and burn blue like the rest of the fuel. If the reaction zone is incomplete however, or not very efficient, the soot can escape the flame without burning at all. Outside the flame, the soot cools quickly to black and drifts away. What do we call this unburnt sooty fuel? You guessed it. Smoke.

1 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

2 waxy   

adj.苍白的；光滑的

参考例句：

• Choose small waxy potatoes for the salad.选些个头小、表皮光滑的土豆做色拉。
• The waxy oil keeps ears from getting too dry.这些蜡状耳油可以保持耳朵不会太干燥。

3 fiery   

adj.燃烧着的，火红的；暴躁的；激烈的

参考例句：

• She has fiery red hair.她有一头火红的头发。
• His fiery speech agitated the crowd.他热情洋溢的讲话激动了群众。

4 combustion   

n.燃烧；氧化；骚动

参考例句：

• We might be tempted to think of combustion.我们也许会联想到氧化。
• The smoke formed by their combustion is negligible.由它燃烧所生成的烟是可忽略的。

5 clump   

n.树丛，草丛；vi.用沉重的脚步行走

参考例句：

• A stream meandered gently through a clump of trees.一条小溪从树丛中蜿蜒穿过。
• It was as if he had hacked with his thick boots at a clump of bluebells.仿佛他用自己的厚靴子无情地践踏了一丛野风信子。

6 soot   

n.煤烟，烟尘；vt.熏以煤烟

参考例句：

• Soot is the product of the imperfect combustion of fuel.煤烟是燃料不完全燃烧的产物。
• The chimney was choked with soot.烟囱被煤灰堵塞了。

7 swirl   

v.(使)打漩，(使)涡卷；n.漩涡，螺旋形

参考例句：

• The car raced roughly along in a swirl of pink dust.汽车在一股粉红色尘土的漩涡中颠簸着快速前进。
• You could lie up there,watching the flakes swirl past.你可以躺在那儿，看着雪花飘飘。