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Sensirion / arduino-i2c-scd4x

Arduino library for Sensirion SCD4x sensors
BSD 3-Clause "New" or "Revised" License
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setSensorAltitude below sea level #35

Closed GlebDen closed 1 month ago

GlebDen commented 2 months ago

Hello. Is it possible to setSensorAltitude below sea level?

abrauchli commented 2 months ago

Hi @GlebDen

Use the fact that the pressure increases by about 1 hPa for every 10 meters you go below sea level along with setAmbientPressure() instead of setSensorAltitude(). Note that you can't use both functions together (whichever is called last is used).

Starting from sea level (1013.25 hPa): For every 10 meters, the pressure increases by approximately 1 hPa. At the Dead Sea shore in Israel, the lowest dry land point on earth at 430 meters below sea level, the increase in pressure would be 430÷10=43 hPa or approximately: 1013.25 hPa+43 hPa=1056.25 hPa

So setAmbientPressure(1056); followed by enjoying some floating in the warm water.

psachs commented 1 month ago

Thanks @abrauchli for the detailed answer. I will close the ticket as everything should be clear now.