OK, I was totally taken in by all the stories which claimed that places in Canada (the original soundbite I heard mentioned Winnipeg) were colder than what the Curiosity rover was experiencing on Mars. It sounded so plausible–and it is possible there are times that the coldest places on Earth can be colder than the warmest places on Mars.
However, the indefatigable team at PolitiFact.com have determined that it is not true right now.
As our own Patricia Vollmer has pointed out, the recent cold spell had some journalists overdosing on hyperbole. The root of the problem here is that the temperature numbers were comparing apples and oranges. So reporting from Winnipeg, Manitoba recorded -31 deg Celsius with the wind chill down to -50 deg C. Some of the most recent data reported by the Mars Curiosity rover measured temperatures of about -30 deg C–so woohoo! Canada is colder than Mars!
Well, not quite.
When we measure temperature and wind chill, we’re measuring the temperature of the air. When Curiosity measures temperature, she’s measuring the temperature of the ground–very different things. When Curiosity measures the air temperature around her it ranges between -198 and -76 deg C–much, much colder than even the recent polar vortex, plus windchill, was producing in Winnipeg.
I have to admit, I got caught up in the hype. And it is still possible that there are times and places where comparing air temperatures will still give you a warmer day on Mars than on Earth. But that didn’t happen this time, and I’ll try to remember to be more skeptical next time. Live and learn!
Thank you for pointing out some fundamental differences in temperature measurement. This is something that we weather geeks need to understand and try to educate about. An official American temperature measurement is conducted at a standardized height, usually at 2 meters, so slightly higher than your standard suburban stockade fence.
I could go on for *days* about how changes in how weather observations are taken has impacts on data inputs to climate models. But that’s for another post/discussion. A prime example is when U.S. reporting sites changed from human observations (i.e., read a thermometer, write it down, read a wind sensor, write it down, etc.) to automated observation systems (no human) in the early 1990s.
Thanks Patricia! Measurement techniques can make a big difference, and it’s always important to make sure you’re comparing apples to apples. I know just in my own lab experience I can usually see my data gathering changing over time if there’s a human in the loop.