Calibrating an Aneroid Barometer

An aneriod (or analog) barometer is a favorite tool for weather enthusiasts. However, aneroid barometers must be routinely calibrated to accurately display atmospheric pressure. Read on to learn more...

Aneroid Barometer Adjustment
Barometers are essential tools for forecasting weather. Without an accurate adjustment, inaccurate data will produce misleading results. When you first get a new aneroid barometer, follow these important procedures:

Local News: Local weather reports on television or the internet will give you an accurate aneroid barometer reading for the area. Take note of this broadcast reading.
Turning the Screw: The back of the aneroid barometer has a hole for a small screwdriver. Place one inside and connect with the adjustment screw.
Accurately Adjust: Turn the screw while watching the dial face, aligning the hands to the proper barometric reading for your area. Always move the indication hands clockwise.

Make the Readings
The key to understanding any barometric reading is measuring the relative change. The center knob on front of the analog barometer lets you do just that. Use that knob to move the inside hand over the barometer's current setting. Using this large hand as a reference point, your aneroid barometer is ready to help predict weather as the small hand moves.

Frequent Adjustments
Periodically check if the reading on your aneroid barometer matches the broadcast reading. Over time, springs in the aneroid barometer mechanism slacken. Frequent adjustment tunes the device back to accuracy.

Interpretation
Aneroid barometer readings make pretty accurate weather forecasts for a 24 hour span.

In general, if the aneroid barometer is not moving, the weather will stay the same. Of course there are many exceptions. But that's what makes weather watching so interesting.