The company also has a popular mobile app, which Mr. Kenny said
collected barometric pressure from its users’ phone sensors.
Millions of locations are turning in information 96 times a day.
The company also has a popular mobile app, which Mr. Kenny said
collected barometric pressure from its users’ phone sensors.
Millions of locations are turning in information 96 times a day.
Well, four years later here we are! Finally. We are at the beginning of a revolution in how we understand our atmosphere. There are now billions of internet-connected barometers that can be used in weather models - this should provide a revolution in our ability to forecast short-term mesoscale events like thunderstorms and tornadoes, among other things [2].
[1]: http://gizmodo.com/5851288/why-the-barometer-is-androids-new...
[2]: http://cliffmass.blogspot.com/2015/10/apple-computer-could-r...
Some startups working on this are Sunshine, PressureNet, Weathermob, WeatherSignal:
The biggest deal is to collect the data. After data arrives, they can then look for any patterns they need. Filter anything that seems wrong.
In the work I've done on this problem we've never been too concerned about inside vs. outside. A much bigger problem is small altitude changes that mess with the exact readings by huge margins, but again, if we're focusing on trends instead of the immediate exact value, we can smooth out the noise relatively easily.
However, to actually answer your question, an app can make a very good guess about whether it is inside or outside. Key sensors and metric for this are: ambient light sensor, humidity sensor, GPS location / barometer. During the day it is normally brighter outside than inside, and during the night is normally brighter inside than outside. So that's clue #1. Clue #2 is to check GPS to see if the user is moving - if you are moving rapidly then you are probably not inside. And if the barometer is rapidly going up and down, but GPS is not changing, then the user is probably inside (elevator, stairs, etc) and that's clue #3.
Again, none of that is necessary to solve for this particular problem, but it's interesting.
Statisticians (et. al) are well versed at receiving a whole bunch of messy data and figuring out the value that they want to observe.
From a rough perspective, I think it would look something like this:
1) There will be a large concentration of people reporting pressures that are on the low side, this is the true outside pressure.
2) There will be clusters of people reporting high pressures, and that will be inside buildings.
3) To ignore funny circumstances where large amounts of people are reporting lower pressures than the true outside pressure (I'm not sure why this might be, but this is not my domain of expertise) you can compare it to the pressure that people are seeing around that area, and to official pressure readings.
Is there a reason why we haven't seen a thermometer in a phone so far?
In fact, every phone does have a thermometer, but that is not usually accessible by developers and it does not measure the actual air temperature - it's used by the phone to make sure it doesn't get too hot from the battery or CPU. We might not see many app-level thermometers get added to phones because the data is extremely difficult to use. For example, most of the time it will measure the temperature in your pocket or in the room where the phone is - and even then, the reading will be radically affected by what the phone is doing (browsing the web is going to cause a different temperature reading compared to watching a video, compared to stand-by mode).
I do expect that we'll see more hygrometers and thermometers and other sensors make their way into phones as time goes on, but I think the primary reason for the slow take-off is because the data is really really hard to use. That's the thing with the barometer - it's very resilient to noise and even when the data has problems, they are fixable.
However, it is now mandated by the FCC that all barometer-carrying smartphones will report your accurate altitude information to 911 emergency response if you make a 911 call from your smartphone. So the location tracking element of the barometer is a very real concern for a lot of people, as it can tell a tracking company what floor of a building you are on at any given moment.
However I think it's quite clear that weather apps, and The Weather Company, are much more interested in the local atmospheric trends than they are about your current floor.
Edit: FCC citation: https://www.fcc.gov/document/fcc-adopts-new-wireless-indoor-...
How can this possibly be true? Wouldn't the pressure around a couple of square meters simply equalize instantly? You're not saying "within a mile" you're saying "to within 1 meter", and I don't get it.
The barometer is sensitive to altitude changes much much smaller than a meter, probably something like 0.1 meters. So if you are a person, with a smartphone, and you are in a tall building, the barometer can assist with determining which floor you're on. Other sensors would need to be used for calibration (since the changes weather will affect the floor-level) and it doesn't help with the x,y coordinates, just the z. But other location systems are now very very good at x,y and they mostly lack the z.
So by adding the high-accuracy relative altitude capabilities of the barometer to the existing x,y systems, you can get extremely precise locations.
permission for location services in general
Also if I'm spending most of my time indoors in buildings, how much of it would affect the readings as compared to when I'm out in the open?
Indoor vs. outdoor isn't really a problem most of the time - the pressure is basically the same inside and outside. A bigger problem is fast altitude changes, which make the absolute reading from the barometer very difficult to interpret safely.
One of the reasons that it took so long for TWC to finally do this is because of the concerns you just voiced: that having this data might actually make the models worse, if they don't take enough care to quality-control it first.
A lot of the research done by scientists (like Cliff Mass at the University of Washington) is how to assimilate this data in a reliable and trusted way. It is likely that The Weather Company does not know how to use the exact pressure readings from the barometer yet (nobody does). Instead, they will probably use the trends over time (say 6 hours), because those are more resilient to noise.