[nix]

More data is nice, but the experience with citizen-operated weather stations suggests that the data is useless without extensive quality control. Calibration is hard, and mobile sensors are particularly challenging. What happens when one of the sensors goes into a climate-controlled building, then takes an elevator to the 30th floor?

[cryptoz]

So, part of this is an experiment. I don't think anybody's done such fast and distributed crowdsourcing of weather data before, so I'm not sure how useful the data will end up being. As far as a single user entering a building, taking elevators, etc, I'm not concerned since those data points will stand out from the nearby readings and can easily be discarded. However, a point raised in another comment here is, what if most users in an area (say Manhattan) are constantly changing elevation. That very well may pose a problem. We'll see. :)