On 01/07/2020 10:14, Ahem A Rivet's Shot wrote:
> On Wed, 1 Jul 2020 10:07:21 +0200
> "R.Wieser"  wrote:
>
>> Assuming that the readout of the sensor is correct (which is an easy
>> assumption, seeing that its carefully calibrated) I must conclude that my
>> (roughly estimated) altitude is the one thats incorrect.
>
>  I refer you to A Dumas' point elsethread - to quote:
>
>> The vertical gradient isn't so precisely fixed, it depends on the
>> temperature. Approximately varies between 11 and 13 Pa per metre at sea
>> level, which means the error might be more than 10% right from the start.
>> See https://en.wikipedia.org/wiki/Barometric_formula
>
>  Add that 10% to your other sources of error and I think you'll find
> you're doing quite well to be as close as you are.
>
For a rough and ready altitude, GPS in your smart phone can tell you to
within about 10 meters

https://play.google.com/store/apps/details?id=com.eclipsim.gpsstatus2&hl=en

I got reading from 95m -115m...

--
  “A leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
“We did this ourselves.”

― Lao Tzu, Tao Te Ching

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