how do you make a home made barometer?

Answer 1

The easiest barometer to make is a classic mercury barometer.
It functions because there is a vacuum above the mercury at the top of the column. Air pressure is what pushes the mercury up the tube. If there is a reduction in the atmospheric pressure, the level of the mercury in the barometer is not as high.
To make one, all you need to do is fill a glass tube with mercury. Use a tube that is more than 750 mm long (about 800 mm will be long enough and that is equal to about 32 inches). Place the open end of the tube into a cup of mercury so th open end is below the surface of the liquid mercury, Be careful to not allow any air into the tube.
Keeping the open (bottom) end of the tube below the surface of the liquid in the cup, stand the tube up vertically.
Suspend (hold or support) the tube so the bottom of the tube is above the bottom of the cup so that the flow into and out of the tube will not be blocked.
Place a measuring device in position so you can measure the distance from the top of the level of the mercury in the cup to the top of the mercury in the tube.
The height of that column of mercury will be equal to the barometric pressure, not corrected to sea level of differences in altitude, but it will be the actual barometric pressure.
NOTE: Don't actually make one. Mercury has a toxic or poisonous quality and a good barometer is not expensive to buy. Other liquids can be used to make a barometer, but due to their lighter weight, a much taller tube will be required and the end measurement will have to be mathmatically corrected to compensate back to a standard mercury barometer measurement.