The Speed of Sound in Air, where you are.
The Cair app calculates the Speed of Sound in Air from the air temperature, air pressure, and air humidity, optionally using the local conditions. If your device supports it, Cair is able to get the local air pressure directly from the device. There are popups to see the values in both metric and imperial units, and you can pick your preferred units for the main display of the values.
Cair can pass its calculated Speed of Sound to another dgApps app, Lambda version 2.0.0 and newer. Lambda can use the Cair calculated Speed of Sound in its calculation of frequency, wavelength, and musical note. Cair is a universal app, equally at home on an iPhone as on a iPad. In Split Mode on an iPad device, side by side with Lambda, the calculated Speed of Sound in Air is passed in real time to the Lambda app.
Cair allows you to share its calculated Speed of Sound in Air via all the usual sharing methods.