130 Degrees in the Shade
Despite the mythology of soldiers “carrying 40 pounds of body armor in 130-degree temperatures” during their tours in Iraq, David Sessions explains, “the highest temperature ever recorded in Asia is 124 degrees—in Dhahran, Saudi Arabia.” Further, since there’s little humidity in the desert, “the heat index won’t be much higher than the actual temperature.”
Veterans of the Vietnam war also bandy about the 130-degree figure but, since Vietnam is in Asia, and it’s never been above 124 degrees there, it can’t be right. (Although, to be fair, it’s humid in the tropics, so the heat index might actually reach that mark.)
Maybe soldiers just like to bitch about how hot it is? Almost certainly. But there’s also a scientific explanation:
Soldiers and travelers often measure the temperature with personal thermometers, which tend to give inaccurate readings. Command posts sometimes place thermometers on their outside walls or other locations within their encampments, but these thermometers are also cheap and unscientific; one solider described them as the kind of thing you’d pick up from Wal-Mart or see in someone’s garden.
But even a perfectly functioning thermometer, if placed on a solid surface, is likely to deliver higher readings than one set up in an open, breezy area. In general, a solid object absorbs more heat than an equivalent volume of air and can rise to a higher temperature given the same amount of sunlight. An instrument placed on sand or concrete will absorb heat from that surface—obscuring (and inflating) the actual air temperature. So, depending on where it’s sitting, a surface thermometer can be off by more than 10 degrees. That’s why professional meteorologists prefer to measure the temperature in a ventilated location, and never set up their instruments on heat-conducting surfaces like sand, concrete, or asphalt.
Indeed, my car has a thermometer which displays external temperatures and I’ve frequently recorded 100-degree plus temperatures this summer, even though we’ve only barely crossed that mark here in the official statistics. The asphalt, though, apparently gets there more often.
UPDATE: Several commenters point out, quite correctly, that our soldiers in Iraq are quite frequently working on sand and asphalt and that, therefore, the fact that the official air temperature in some breezy location is of small comfort.
John Burgess adds another wrinkle:
Governments have laws or regulations that prohibit laborers from working when the outside temperature exceeds a certain point. (See Standing Up for Laborers in the Saudi Summer)
If the Weather Bureau says it’s above the set point, then millions of dollars of work isn’t getting done. The higher the temperature rises above the limit, the harder it is for the Weather Bureau to dissimulate. But it’s amazing how temperatures only rarely rise above the legal limit.
Interesting. While I”m well aware that government statistics are often skewed for a variety of reasons, especially in the developing world, it had never occurred to me that they’d lie about something as innocuous as temperature data.