At last night's Android 4.0 Ice Cream Sandwich announcement we were told that the new flagship phone, the Galaxy Nexus, would include a barometer, and that the Android 4.0 Ice Cream Sandwich SDK included all the bits needed for developers to tie into the new sensor.
What's a barometer?
Wikipedia describes a barometer as "a scientific instrument used in meteorology to measure atmospheric pressure." It measures the pressure exerted by the atmosphere above it. This measurement of pressure can be used to forecast short term changes in the weather and can be used to estimate altitude.
Smartphone Application: Weather Forecasting
HTC's Sense UI includes an iconic "clock and weather" widget prominently featured on the homescreen. Other app developers have created similar widgets, such as Beautiful Widgets, pictured below.
These widgets use your smartphone's geo-location information and your Internet connection to retrieve local weather information (current, high, and low temperatures; and current conditions) for various weather data providers. Using the same information you can get the weather forecast for the next several days.
Augmenting those with real-time, local, barometric pressure readings may allow these types of apps to be even more reactive to changes in the weather.
Currently, I have Beautiful Widgets set to check on the weather every four hours. Checking more frequently can drain your battery and chew up your data. No, it's not much of either, but when added up, over time your data usage could go up (a problem for those not on "unlimited" plans) and your battery life could go down (a problem for all of us).
Imagine this scenario: you're sitting at your desk, perfectly content in your short-sleeved shirt, and want to run to lunch. You check your smartphone and the forecast says you'll have a storm front roll in sometime in the early evening, so you don't worry taking your coat or umbrella. You head out to lunch. Unfortunately, like me, you set your smartphone to update the weather forecast every four hours; it's been three hours since the last update. Since then, that cold-weather front has moved in faster than anticipated. You find yourself caught in a heavy rainstorm with blowing winds that wasn't supposed to arrive until your commute home.
With a barometer built into your phone, and an app which can read its data, your smartphone could have noticed the drop in barometric pressure and alerted you to the change. It could also have triggered a request to update forecast data, saving your battery and data usage by only updating when the weather changed.
If your phone had a barometer in it, and your weather app was programmed to use changed in barometric pressure to trigger an update, perhaps you could have avoided getting caught out in the rain.
Additionally, since a barometer isn't dependent upon a data connection, you could still get "weather change alerts" even when you weren't under a data umbrella. Such as...
Smartphone Application: Altitude
.. when you're hiking.
My family and I like to go hiking in the foothills and mountains around us. Last week my son and I hiked several miles each day in unfamiliar territory. We were in a very remote area which was outside not only data coverage, but cellular voice coverage as well.
We used Google's My Tracks to chart our progress while hiking, and so we could see where we were in relation to where we started (in case we got lost). We didn't have any digital maps of the area (again, we had no data coverage), we could only see the line of where we'd walked, but that was useful enough.
On one of our hikes we were approaching 10,000-feet above sea level. The temperature drops pretty quickly when you're up that high, and weather can change quickly — very quickly. We didn't know we were that high, at the time we thought we were only about 8,800-feet up... 1,200-feet makes a lot of difference.
Since we had the GPS on and recording our track, a quick glance at the data during one of our breaks showed us our true altitude, so we were a little more cautious and aware of the weather, but if we hadn't been recording our tracks we wouldn't have known, and we could have gotten caught in a bad situation.
Since many people turn off the GPS on their phone to conserve battery life (especially when they're not actively using it), someone in a similar situation might not have known, and that bad situation could have become a major problem!
A barometer is a passive sensor (rather than an "active" sensor, like GPS). An app could alert you to your altitude when you approach certain thresholds — without sucking down your battery like GPS does. Perhaps apps like My Tracks could be updated to include an "altitude trigger" option, which could turn on the GPS to record your location at 50-foot increments of elevation change, saving your batter, but still recording a relatively accurate track.
Since you're wondering...
That day's hike could have gotten bad. We were only around three-miles from the trail-head, but we had climbed over a thousand-feet in elevation, and were still headed up the mountain. We didn't know at the time, but a storm-front was moving in, and the pressure was dropping — fast. Since there was a mountain in the way, we couldn't see the impending storm-front closing in on us, and at that altitude, we were a lot more exposed than we thought we were.
If we'd have been at the top of the trail when the storm rolled in (or if there had been rain or snow with it), we could have been in trouble.
If one of us had had the Galaxy Nexus with an app running and set to sound an alert when the barometric pressure dropped, we'd have gotten off the mountain a lot faster than we did — and all without needing any data coverage.
As luck would have it, we got to the bottom of the trail just as the leading edge of the storm was upon us. It brought wind and clouds and sent the temperature down ten-degrees Fahrenheit in a matter of minutes. With clouds blocking the sun and the wind picking up we started to get cold — but we were safe.
What else can you think of that a barometer could be used for on a smartphone? Let your imagination run wild and let us know what you think in the comments!