As an example we are in Sao Paulo at a height of about 800 m above see level.
Interesting question. I have never has such problem. I have the luyxury that I leve in The Netherlands. My house fundament is 12m above see level.
Country is highly populated - I have at least 3 profesional/goverment meteological station in radius of 12km . One semi professional station is just 1km from me.
I have 3 BME280 - the absoulte atmosferic pressiure seems to be prety close - best time to do this by steady state wether - the most meteo stations give the same air air presure - normalized to altitude /Happily the altidude diference here is just 10..15meters./.
It was interesting that the absolute air pressure value is prety close to the government stations data.
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I cannot say the same for humidity - forest,my small vilige, agriculture area, lakes and rivers has different RH - I experiance it with naked eye in foggy weather
I cannot say the same for temperature - I cannot achieve equal temperature even at 10mm distance
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I'm not expert in this areay but fast google search shows that relative humidity calculation from dew point is independent from air pressure
- the only requirement is that dew point chamber mus have the same .
- mathematical explanation - The two part of equation neutralize the air pressure
- engineer/my/ explanation
1. RH is function of air pressure. Ideal air P*V=const
2. Dew point occurs when liquid pressure >= air pressure
1 & 2 neutralize each other
https://lambdageeks.com/dew-point-and-pressure/https://www.orionkikai.co.jp/english/technology/kuatsu/dewpoint-temp/https://en.wikipedia.org/wiki/Dew_point