So what about barometer and altimeter?

Barometer

Atmotube PLUS/PRO has barometer and altimeter functions. The device reports atmospheric pressure and altitude in real time. Atmotube PRO also predicts the weather based on the change in atmospheric pressure according to the algorithm in table below.

Barometer (Reduced to Sea Level) Wind Direction Character of Weather Indicated
30.00 to 30.20, and steady westerly Fair, with slight changes in temperature, for one to two days.
30.00 to 30.20, and rising rapidly westerly Fair, followed within two days by warmer and rain.
30.00 to 30.20, and falling rapidly south to east Warmer, and rain within 24 hours.
30.20 or above, and falling rapidly south to east Warmer, and rain within 36 hours.
30.20 or above, and falling rapidly west to north Cold and clear, quickly followed by warmer and rain.
30.20 or above, and steady variable No early change.
30.00 or below, and falling slowly south to east Rain within 18 hours that will continue a day or two.
30.00 or below, and falling rapidly southeast to northeast Rain, with high wind, followed within two days by clearing, colder.
30.00 or below, and rising south to west Clearing and colder within 12 hours.
29.80 or below, and falling rapidly south to east Severe storm of wind and rain imminent. In winter, snow or cold wave within 24 hours.
29.80 or below, and falling rapidly east to north Severe northeast gales and heavy rain or snow, followed in winter by cold wave.
29.80 or below, and rising rapidly going to west Clearing and colder.

Note: A barometer should be adjusted to show equivalent sea-level pressure for the altitude at which it is to be used. A change of 100 feet in elevation will cause a decrease of 110 inch in the reading.

Altimeter

The default altitude value is set by the GPS data (if GPS is enabled in the settings).

Atmospheric pressure vs height
  • p0 - Calculated mean sea level pressure
  • p - Measured/barometric pressure
  • h - Elevation of measured data
  • T - Measured air temperature

Altitude is also calculated based on the difference between current atmospheric pressure and pressure at mean sea level. Every 8.8 meters atmospheric pressure drops by 1 mbar.

Atmospheric pressure formula

Pressure at mean sea level is received from the weather server based o GPS location. This value can also be entered manually.


Mean sea level rate calculator (converter).