【英语时差8,16】飞机及其超音爆

 Aircrafts And Their Supersonic Boom This time we’ll look at how the size and altitude of a plane influence the intensity¹ and duration of the sonic boom. The sonic boom is a direct result of a change in the air-flow pattern around a plane’s edges. The moment a plane hits speeds faster than about 768 miles per hour, or the speed of sound, it creates shock waves that travel in all directions. When these shock waves hit the ground, we hear a sonic boom. As a general rule, the bigger the aircraft, the larger the shock waves and the longer the duration of the sonic boom. The smallest aircraft capable of traveling faster than the speed of sound generates a boom that lasts one twentieth of a second. The largest supersonic aircraft creates a boom that lasts ten times longer, or half a second. However, two aircraft the same size flying at different altitudes will create sonic booms of different intensities². A craft flying higher will create a less intense sonic boom at ground level, because the shock waves have farther to travel before hitting the ground, and therefore have more time to dissipate. The sonic boom created by this high flying plane will be heard by a larger geographic³ area than the boom created by a low flying plane because as the shock waves travel to the ground, they spread out and increase the radius⁴ they affect. Luckily, even the most intense sonic booms can’t hurt people, but they have been known to damage plaster walls and break windows.

1 intensity   

n.强烈，剧烈；强度；烈度

参考例句：

• I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。
• The strike is growing in intensity.罢工日益加剧。

2 intensities   

n.强烈( intensity的名词复数 )；（感情的）强烈程度；强度；烈度

参考例句：

• At very high intensities, nuclear radiations cause itching and tingling of the skin. 当核辐射强度很高时，它能使皮肤感到发痒和刺痛。 来自辞典例句
• They ask again and again in a variety of ways and intensities. 他们会以不同的方式和强度来不停地问，直到他得到自己想要的答案为止。 来自互联网

3 geographic   

adj.地理学的，地理的

参考例句：

• The city's success owes much to its geographic position. 这座城市的成功很大程度上归功于它的地理位置。 来自《简明英汉词典》
• Environmental problems pay no heed to these geographic lines. 环境问题并不理会这些地理界限。 来自英汉非文学 - 环境法 - 环境法

4 radius   

n.半径，半径范围；有效航程，范围，界限

参考例句：

• He has visited every shop within a radius of two miles.周围两英里以内的店铺他都去过。
• We are measuring the radius of the circle.我们正在测量圆的半径。