>smartphones. They have barometric data

For anyone else having a TIL moment: It's apparently for vertical position and supposedly sub meter accurate. o_O

Depends on smartphone (and smartwatches). Not all have it, at times it disappeared from brands that had it earlier.

The smartwatch series I use explicitly include it because it's essentially the "all in one" version in a series that had smartwatches designed for aircraft use (including military versions where they serve as backup cabin pressure warning, apparently)

Smartwatches include barometers because they enable elevation measurement far more accurate than than GNSS (GPS and GPS-alikes, they tend to be noticeably less accurate in the vertical than in the horizontal). In particular when both are combined: barometry for high frequency changes (going up a hill) continuously calibrated against a long term average of the GNSS elevation to filter out low frequency changes in barometry (weather influence).

But back to device could weather observation, this would require continuous GNSS, devices don't do that (network location would not be good enough).

Dark Sky used that data for hyper local forecasting…

https://news.ycombinator.com/item?id=22740466

https://www.theverge.com/2015/6/22/8822767/dark-sky-weather-...

I'm still grumpy about apple buying and shuttering darksky

They stopped using it during later years.

Not really; it was a gimmick. They used standard forecast post-processing techniques to bias correct global/regional weather models. There is virtually no evidence they actually used device data in this process.

"Collecting and processing of barometric data from smartphones for potential use in numerical weather prediction data assimilation"

https://rmets.onlinelibrary.wiley.com/doi/10.1002/met.1805

https://github.com/dmidk/smaps