Flying through the Midwest in the summertime means one thing: turbulence. Just after a teenager girl had entered the bathroom, we hit a patch of very rough air. After the bumps had subsided, she exited the bathroom, a look of sheer terror etched on her face. “Are you all right?” I asked. “That turbulence was so bad.” “So that's what it was,” she said. “I thought I'd pushed the wrong button.”

夏天在美国中西部飞行就代表一件事：涡流。一个十几岁的女生刚进到洗手间，我们的飞机就遇到一整片十分不平稳的气流。等颠簸平复下来以后，她从洗手间里出来了，满脸害怕的样子。我问她：“你不要紧吧？这股涡流可够厉害的。”她说：“原来是这样一回事。我以为是因为我按错了开关。”