Density Altitude & Air Density

WIDGETS, LOCK SCREEN AND APPLE WATCH Your featured value — density altitude, RAD or air density — on the Home Screen, the Lock Screen and your watch face, always with how old the data is. During a session it is also a Live Activity on the Lock Screen and in the Dynamic Island. ALERTS WHEN CONDITIONS CHANGE Turn them on for a session and the app tells you when air density moves by your threshold since the first reading, with the new density altitude. Forecast-based alerts arrive even with the app closed. CARBURETOR ICING A warning from temperature and dew point on the chart used in civil aviation, read for a ground engine at full throttle or for an aircraft, as you choose. BIG READING Your value full screen, high contrast and full brightness, to read at arm's length. SHARE A READING By link, file or QR code, with nothing personal in it. Without the app, it opens in the browser. ICLOUD Your sessions and settings on all your devices. ALSO • The app now opens in your iPhone's language. • On iPads without GPS and indoors, the app no longer waits forever for a position. • Altimeter setting (QNH) fixed: it is now computed from station pressure. • Report a problem from inside the app. IN EARLIER VERSIONS 2.1 — Complete rebuild: the iPhone barometer, session logging with chart and CSV, 4 dyno correction standards, wider ranges, grains per cubic foot, dark mode and iPad.

Air density, density altitude (DA) and relative air density (RAD), computed with the precision that tuning an engine or planning a takeoff actually needs. WHY THIS APP • The barometer in your iPhone: the real pressure where you stand, with no network. • Density altitude, RAD or density on your widgets, Lock Screen and Apple Watch. • Alerts when conditions change during a session, even with the app closed. • Carburetor icing, read for a ground engine or for an aircraft. • Session logging with chart, CSV export and iCloud sync. • 4 dyno correction standards, so the factor matches your dyno sheet. • The full CIPM equation used in metrology, not an ideal-gas shortcut. WHAT IT CALCULATES • Air density (kg/m³, lb/ft³, lb/gal US, gr/ft³) • Density altitude • Relative air density (RAD) • Relative horsepower • Dyno correction factor • Dew point • Virtual temperature • Altimeter setting (QNH) • Actual station pressure WHO IT'S FOR Jetting and carburetion. Size your jets on a kart, bike, scooter or race car for the conditions you actually have today, and build proper jetting charts instead of guessing. Dyno testing. Apply the correction factor to compare runs from different days and know how much of the difference was the engine and how much was the air density. Drag racing. Density altitude and RAD for the run, before you stage. Aviation and RC flying. Density altitude and altimeter setting for takeoff performance, and the carburetor icing chart read the aviation way. Precision shooting. Track air density through the day and adjust your loads as conditions move. Golf. How far the ball actually carries in today's conditions. LOG THE DAY Record a session and see on a chart how conditions change through the day, with the change since the first reading. Export it as CSV, and find it on your iPad too through iCloud. ALWAYS IN VIEW Widgets on the Home Screen and Lock Screen, Apple Watch complications and, during a session, a Live Activity: your featured value with how old the data is. With the forecast, the widget moves ahead hour by hour. ALERTS During a session the app can let you know when air density moves by 0.5, 1, 1.5 or 2 % since the first reading, or when carburetor icing becomes a risk. Never at night, and never more than six a day. CARBURETOR ICING The temperature and dew point placed on the four-zone chart used in civil aviation. For a kart, bike or dyno, only the full-throttle risk; for an aircraft, the four zones with their aeronautical reading. SHARE A READING Send a reading by link, file or QR code. Whoever has the app opens it in the app; whoever doesn't, in the browser. WHERE THE DATA COMES FROM Three sources, and you always know which one you are on. The barometer built into your iPhone, for the real pressure right where you stand. The nearest weather station, for temperature, pressure and humidity. Or type it all in by hand. The hourly forecast comes from Apple Weather. UNITS Pressure in mb, hPa, mmHg or inHg. Temperature in ºC or ºF. Altitude in metres or feet. Density in kg/m³, lb/ft³, lb/gal (US) or gr/ft³ for precision shooting. PRIVACY No account, no analytics, no tracking. Your sessions stay on your device and, if you turn it on, in your own iCloud, which nobody else can read. Your location is used only to look up the weather: rounded to about 110 m, it goes to the ISEnet weather service and, for the forecast, to Apple Weather, never linked to you. Available in 10 languages: English, Spanish, German, French, Italian, Portuguese, Russian, Japanese, Polish and Dutch.