On Friday I was walking by the Tishman building and overheard a guy brandishing what I thought was a pistol-shaped photographic spotmeter, telling another guy – “hey, get a load of this”. Naturally I stopped to take a look. The instrument turned out to be not a spotmeter, but a Raytek Raynger ST , a noncontact thermometer used by air conditioning professionals to check temperatures at different points in buildings. The guy pointed it at the sidewalk, cars and skyscrapers, reading a normal range of temperatures. But when he pointed it at the sky, the Raynger showed a temperature of approximately -30. It’s very cold up there, isn’t it?