I really love the idea of crowdsourced meteorological data. I can envision a world where every smartphone has a lower power barometer and ambient temperature and humidity sensors. Combine this with lower power GPS and you could have the majority of the world's citizens constantly transmitting basic atmospheric data 24/7. As sensors become more advanced and cheaper, one can even envision a time when smartphones also include things like air quality sensors and so forth.
I can't imagine how accurate our weather forecasting would become if we had constant access to this incredible amount of real-time data.
The problem is that the effect of being in a pocket is not zero-biased when it comes to temperature (and possibly also humidity). You'd see temperatures being pulled towards normal body temperature on average.
Yes, but in my rudimentary understanding of weather the importance is the pressure differential rather than the absolute pressure.
I believe the data in aggregate will provide a pretty good map of the pressure gradient which could then be fixed to the more accurate dedicated weather stations. Think of it like the 10,000 year clock which uses a clock known to drift in conjunction with a solar time fix to calibrate.
Right, it's generally believed that forecasting will never be effective beyond about 15 days, due to amplification of small uncertainties by the nonlinear atmosphere dynamics. Predictability is better in the tropics by a couple of days, and better in the northern hemisphere winter by a couple of days.
It's worth noting that the pressures measured, even if they could be calibrated, would be almost entirely on land, and only at the surface of the Earth, not at higher altitudes (it is, of course, a 3D problem). And also, a lot more than just pressure is needed -- temperature, wind velocity, clouds, aerosols, irradiance, ocean currents, wave height, soil moisture, ...