单位换算的尴尬

请看一段新闻：

Record snowfall brings Beijing and Seoul to a standstill (破纪录的暴雪使北京和汉城交通瘫痪）

Tania Branigan in Beijing guardian.co.uk, Monday 4 January 2010 12.59

Thousands of schools closed and hundreds of flights cancelled in China and South Korea as roads paralysed by ice and snowPunishing winter weather buffeted China and South Korea today, with Seoul residents experiencing the heaviest snowfall in modern history.

Biting cold, ice and snow have paralysed roads and caused the cancellation of hundreds of flights in north Asia since the weekend. In China, more than 2.2 million pupils in Beijing and nearby Tianjin enjoyed a day off as officials took the rare step of closing thousands of schools.

Temperatures in the Chinese capital are expected to fall to -18C (-32F) tonight, with predictions they could reach -32C in the northernmost parts of the country by Wednesday morning. （下略）

这最后一段的大意意是：中国首都的温度将会降到摄氏零下18度（华氏零下32度）。这个记者在这里犯了一个科学家和工程师们也会犯的错误，即简单地将摄氏温度值乘上1.8的系数（18x1.8=32.4）。实际上，温度应该是华氏零度。更准确一点，是零下0.4度。我二十多年前听一个教授给研究生讲课，他就是这样简单地换算温度的,忘了不同的温度单位，其起点值不同，摄氏零度时，华氏是32度。 我做了一个单位换算计算器，只要将某种单位的温度输入，就可以得到相应的其他三种温度值。