How to Set a Barometer
Buy a barometer., Obtain a local reading of barometric pressure., Set the indicator hand on your barometer., Hang the barometer in a location that works for you., Check occasionally to be sure that your barometer works properly., Set the manual hand...
Step-by-Step Guide
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Step 1: Buy a barometer.
There are three types of barometers that can be purchased.
If you own an antique barometer is most likely mercury or aneroid.
Aneroid or electronic barometers are more commonly available for purchase.
Before purchasing a barometer, check their altitude usage.
Not all barometers function properly at high altitudes so buy one that can specifically be used at altitude if you live high above sea level.
Here are some brief descriptions of each type of barometer:
Mercury:
The mercury barometer, sometimes called stick barometer, was the first to be invented.
It uses an open tube system with a pool of mercury that raises and lowers with pressure changes.
They only work at an altitude up to 1,000 feet.Aneroid:
The aneroid barometer doesn’t use any liquids.
It uses a small box made from beryllium and copper that expands or contracts based on pressure changes.
These motions cause mechanical hands to move pointing towards the current air pressure.
Electronic:
Electronic barometers are a little more complicated to understand, but they employ sensors and strain gauges that cause changes in voltage that can be converted to a display of pressure for the user. -
Step 2: Obtain a local reading of barometric pressure.
If using an aneroid barometer, you will need calibrate it to your location.
Listen to a local weather forecast to find the current barometer pressure for your location.
Make sure the reading is correct for your location.
Even a few miles can affect a barometer reading.
Setting your barometer to your location will take into account differences in pressure caused by the altitude of your location.
The factory setting for aneroid barometers is at sea level, but if you don’t live at sea level, you will need to calibrate it., Locate the small adjusting screw on the back of your barometer.
With a small screwdriver, turn the adjusting screw to move the hand to your location's current pressure.
Watch the face of the dial and stop turning the screwdriver when the hand reaches the appropriate reading.
If you are using a mercury barometer, you will have to use a conversion for your readings.
Digital barometers have sensors to calibrate altitude automatically. , It makes no difference whether the barometer is hung on an inside or an outside wall.
The pressure will be the same no matter where it hangs.Avoid locations that have frequent temperature changes such as near a bathroom or heater.
Well-sealed and air-conditioned rooms are not as affected by changes in air pressure, so avoid these rooms if possible.
Avoid a location that is exposed to direct sunlight as the temperature changes can affect the readings.
Hang the barometer away from drafty locations, like near a door or a window.
Air pressure is too variable in these locations. , If you suspect inaccurate readings, you can check your barometer with an easy trick.
With the barometer hanging on the wall, slowly slide the bottom of it sideways to a 45-degree angle.If you have a stick barometer, the mercury should rise to the top of the tube and produce an audible "tick" sound that you may also feel.
The tube should fill with mercury.
If you have an aneroid barometer, the indicator hand should rotate clockwise around the dial.
If your barometer fails this test, you may need to have it professionally serviced and re-set before you can count on its accuracy.
However, most barometers can last years with no servicing. , Turn the barometer's center knob so that the arrow rests directly above the indicator arrow (this is the current barometric pressure for your location).
You can identify the set hand by its notched arrow about halfway down the hand.The set hand will serve as a reference that allows you to easily tell if the pressure is steady, rising or falling.
Remember, this hand will only be present on an aneroid barometer.
If you have an electronic barometer, you can simply check the reading.
If you have a mercury barometer, you will need to correct for altitude if you’re above sea level. , To accurately measure the air pressure using a stick barometer, you will need to correct for your altitude using a conversion chart.Look at the barometer at eye level and record the number next to the top of the mercury.
This is the pressure in millimeters of mercury (mmHg).
Find your elevation and then use to the chart to find the relevant correction factor.
Add the correction factor to the reading on the barometer.
This reading should match the reading of the local weather service.
If you are at an elevation of over 1,000 ft, stick barometers do not work., Predicting weather using a barometer is all about changes in air pressure.
You want to check the reading every few hours to determine if the pressure is changing or staying the same.
If using an aneroid or mercury barometer, gently tap the face of the barometer to release any pressure changes stored in the mechanisms.
Take the reading after the needle or mercury has stopped moving.
Move the set hand if the pressure has changed so the next time you check it will be obvious what direction the air pressure is going. , Keep a journal of all the readings you take with your barometer.
Sketch a small graph for the changes in a day to help with your forecasting.
Is the pressure rising? Falling? Staying the same? This is all important information for predicting the weather.Do not expect large changes in the movement of needle.
Daily changes are usually between
0.02 and
0.10 of an inch using the barometer scale.
Larger variations may occur in winter and are dependent upon location and altitude.Take frequent readings (every few hours) and plot them on your graph. , Generally, if the pressure is falling, the weather is taking a turn towards storms and rain.
The starting point of the reading is also important in the forecast.
Higher readings indicate better weather even if the pressure is falling.If the reading is over
30.2 inches of mercury and falling rapidly, this indicates cloudy, but warmer weather.
If the reading is between
29.8 and
30.2 inches of mercury and falling rapidly, rain is most likely on the way.
If it’s under
29.8 inches of mercury and falling slowly, rain is likely; if it’s falling rapidly, a storm is imminent. , As the air pressure rises, the weather tends to improve as the high pressure systems moves through your location.Readings over
30.2 inches of mercury that rise indicate that the weather will continue to be fair.Readings between
29.8 and
30.2 inches of mercury that rise indicate that the weather will remain whatever it presently is.
Readings under
29.8 inches of mercury that rise indicate that the weather is clearing, but will be cooler. , Steady air pressure indicates long periods of nice weather and suggests that you will be experiencing more of the same.
If it’s sunny and the pressure is holding, expect more sunshine! Higher pressures indicate warmer weather, while lower pressures indicate cooler weather.A strong high pressure system is around
30.4 inches of mercury.
Anything above 30 is considered high pressure.A typical low pressure system is around
29.5 inches of mercury.
Anything below
29.9 is considered low pressure. -
Step 3: Set the indicator hand on your barometer.
-
Step 4: Hang the barometer in a location that works for you.
-
Step 5: Check occasionally to be sure that your barometer works properly.
-
Step 6: Set the manual hand to the current reading.
-
Step 7: Correct for altitude if using a stick barometer.
-
Step 8: Check the barometer an hour later.
-
Step 9: Chart the changes in pressure.
-
Step 10: Predict rain if the air pressure is falling.
-
Step 11: Forecast improving weather when air pressure rises.
-
Step 12: Forecast fine weather when air pressure is steady.
Detailed Guide
There are three types of barometers that can be purchased.
If you own an antique barometer is most likely mercury or aneroid.
Aneroid or electronic barometers are more commonly available for purchase.
Before purchasing a barometer, check their altitude usage.
Not all barometers function properly at high altitudes so buy one that can specifically be used at altitude if you live high above sea level.
Here are some brief descriptions of each type of barometer:
Mercury:
The mercury barometer, sometimes called stick barometer, was the first to be invented.
It uses an open tube system with a pool of mercury that raises and lowers with pressure changes.
They only work at an altitude up to 1,000 feet.Aneroid:
The aneroid barometer doesn’t use any liquids.
It uses a small box made from beryllium and copper that expands or contracts based on pressure changes.
These motions cause mechanical hands to move pointing towards the current air pressure.
Electronic:
Electronic barometers are a little more complicated to understand, but they employ sensors and strain gauges that cause changes in voltage that can be converted to a display of pressure for the user.
If using an aneroid barometer, you will need calibrate it to your location.
Listen to a local weather forecast to find the current barometer pressure for your location.
Make sure the reading is correct for your location.
Even a few miles can affect a barometer reading.
Setting your barometer to your location will take into account differences in pressure caused by the altitude of your location.
The factory setting for aneroid barometers is at sea level, but if you don’t live at sea level, you will need to calibrate it., Locate the small adjusting screw on the back of your barometer.
With a small screwdriver, turn the adjusting screw to move the hand to your location's current pressure.
Watch the face of the dial and stop turning the screwdriver when the hand reaches the appropriate reading.
If you are using a mercury barometer, you will have to use a conversion for your readings.
Digital barometers have sensors to calibrate altitude automatically. , It makes no difference whether the barometer is hung on an inside or an outside wall.
The pressure will be the same no matter where it hangs.Avoid locations that have frequent temperature changes such as near a bathroom or heater.
Well-sealed and air-conditioned rooms are not as affected by changes in air pressure, so avoid these rooms if possible.
Avoid a location that is exposed to direct sunlight as the temperature changes can affect the readings.
Hang the barometer away from drafty locations, like near a door or a window.
Air pressure is too variable in these locations. , If you suspect inaccurate readings, you can check your barometer with an easy trick.
With the barometer hanging on the wall, slowly slide the bottom of it sideways to a 45-degree angle.If you have a stick barometer, the mercury should rise to the top of the tube and produce an audible "tick" sound that you may also feel.
The tube should fill with mercury.
If you have an aneroid barometer, the indicator hand should rotate clockwise around the dial.
If your barometer fails this test, you may need to have it professionally serviced and re-set before you can count on its accuracy.
However, most barometers can last years with no servicing. , Turn the barometer's center knob so that the arrow rests directly above the indicator arrow (this is the current barometric pressure for your location).
You can identify the set hand by its notched arrow about halfway down the hand.The set hand will serve as a reference that allows you to easily tell if the pressure is steady, rising or falling.
Remember, this hand will only be present on an aneroid barometer.
If you have an electronic barometer, you can simply check the reading.
If you have a mercury barometer, you will need to correct for altitude if you’re above sea level. , To accurately measure the air pressure using a stick barometer, you will need to correct for your altitude using a conversion chart.Look at the barometer at eye level and record the number next to the top of the mercury.
This is the pressure in millimeters of mercury (mmHg).
Find your elevation and then use to the chart to find the relevant correction factor.
Add the correction factor to the reading on the barometer.
This reading should match the reading of the local weather service.
If you are at an elevation of over 1,000 ft, stick barometers do not work., Predicting weather using a barometer is all about changes in air pressure.
You want to check the reading every few hours to determine if the pressure is changing or staying the same.
If using an aneroid or mercury barometer, gently tap the face of the barometer to release any pressure changes stored in the mechanisms.
Take the reading after the needle or mercury has stopped moving.
Move the set hand if the pressure has changed so the next time you check it will be obvious what direction the air pressure is going. , Keep a journal of all the readings you take with your barometer.
Sketch a small graph for the changes in a day to help with your forecasting.
Is the pressure rising? Falling? Staying the same? This is all important information for predicting the weather.Do not expect large changes in the movement of needle.
Daily changes are usually between
0.02 and
0.10 of an inch using the barometer scale.
Larger variations may occur in winter and are dependent upon location and altitude.Take frequent readings (every few hours) and plot them on your graph. , Generally, if the pressure is falling, the weather is taking a turn towards storms and rain.
The starting point of the reading is also important in the forecast.
Higher readings indicate better weather even if the pressure is falling.If the reading is over
30.2 inches of mercury and falling rapidly, this indicates cloudy, but warmer weather.
If the reading is between
29.8 and
30.2 inches of mercury and falling rapidly, rain is most likely on the way.
If it’s under
29.8 inches of mercury and falling slowly, rain is likely; if it’s falling rapidly, a storm is imminent. , As the air pressure rises, the weather tends to improve as the high pressure systems moves through your location.Readings over
30.2 inches of mercury that rise indicate that the weather will continue to be fair.Readings between
29.8 and
30.2 inches of mercury that rise indicate that the weather will remain whatever it presently is.
Readings under
29.8 inches of mercury that rise indicate that the weather is clearing, but will be cooler. , Steady air pressure indicates long periods of nice weather and suggests that you will be experiencing more of the same.
If it’s sunny and the pressure is holding, expect more sunshine! Higher pressures indicate warmer weather, while lower pressures indicate cooler weather.A strong high pressure system is around
30.4 inches of mercury.
Anything above 30 is considered high pressure.A typical low pressure system is around
29.5 inches of mercury.
Anything below
29.9 is considered low pressure.
About the Author
Charles Sanchez
Experienced content creator specializing in home improvement guides and tutorials.
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