Air pressure, humidity, air viscosity, temperature, all affect a scale. Scales vary wildly if left uncalibrated. It seems that precision scale manufacturers can't even define exactly how, and just recommend frequent calibration.
Any singular analysis would be insufficient, as there are many properties of the air. Variances in scales can and do occur far greater than the fraction of a degree sought in the experiment. The experiment needs to be done in a vaccum chamber.
A vacuum chamber is not needed. You zero the scale first with air already factored in, then measure the weight of a specific mass. This effectively throws out any variations due to air pressure or density.
Can a FEer explain how there is less gravitational force at the equator than at the poles?
They don't calibrate the scales. See the article posted.
https://wiki.tfes.org/Weight_Variation_by_LatitudeThere are additional factors beyond lattitude that influence gravitational force. There areas on Earth with more density that have a greater gravitational pull. The nome experiment reflects thi
That one is addressed in a different article:
https://wiki.tfes.org/GravimetrySome interesting quotes there. The gravimeter is really a seismometer and it is detecting signals in the low frequency band as 'gravity waves' and 'infra-gravity waves' under a theory that gravity would cause variations as picked up by a seismometer. The gravity anomalies seem to be correlated with the seismic zones of the world.
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If a 1kg weight is measured with the same precise scale at the same lattitude with the passage of low and high atmospheric pressure and it resulted in the same measurement, you would have to concede that atmospheric pressure changes are not why things weight more at the equator.
Here's the other weight experiment done with a properly calibrated scale measuring at different lattitudes.
I think you wouldn't accept it anyway, would you? You still wouldn't be able to explain it.