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How Does a Barometer Work?

Answer #1

Level 3 (with higher mathematics)
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A simple barometer works by using the barometer formula, which relates the height \(h\) above the ground to the air pressure \( \mathit{\Pi} \) prevailing at that height:

Formula anchor
Pressure-Height Graph of a Fluid (Air)
Exponential decrease of pressure with height.

Here \( H ~=~ 8005 \, \mathrm{m} \) and the mean air pressure at sea level is \(\mathit{\Pi}_0 = 101 \, \mathrm{kPa} = 1 \, \mathrm{bar} \). The formula states that the air pressure decreases exponentially with increasing height \( h \).

So an barometer measures the air pressure \( \mathit{\Pi} \) and calculates from it the height at which this air pressure prevails:

Formula: Air pressure
Formula anchor