"Tauno Voipio"  wrote in message
news:q0dal9$ccm$2@dont-email.me...
> On 31.12.18 13:15, NY wrote:
>> "Axel Berger"  wrote in message
>
>> It's interesting to hear people say that variations in pressure caused by
>> gusts are sufficiently small that they do not swamp the variation of
>> pressure with altitude. Without doing the sums, I don't know how much the
>> pressure varies with altitude, but my gut feeling (which is evidently
>> wrong!) would have been that it was smaller than the variations every
>> time there is a gust of wind. Good thing that it's not the case,
>> otherwise pressure-driven altimeters would be unusable.
>
> The altitude change with pressure in standard conditions near
> sea level is -27 ft/millibar (or -8.1 m/mb).

And how much does the pressure change, second by second, due to gusting and
localised turbulence etc? Presumably much less than this or the altimeter
needle would be flickering visibly and would be difficult to read.

Some time I'll have to take the base station (*) of my weather station
outside when it's windy and see what variation in pressure it records,
though I'm not sure what electronic averaging there is between pressure
sensor and digital display. Indoors it's shielded by the house walls so
gusting isn't an issue.

I wonder if I could see a measurable difference between the weather station
on the ground floor and in the attic. My weather station reports pressures
to the nearest 0.1 mb, so *in theory* height differences between one floor
and another ought to be detectable since 0.1 mb is about 80 cm.


(*) A remote sensor unit is used for ext temp and humidity, rainfall and
wind speed/direction, but the pressure is sensed in the base station that is
linked wirelessly to the remote unit and by USB to my PC.

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