Barometers: How they predict the weather

October 18, 2024

A Barometer is a weather monitoring instrument used to measure atmospheric pressure. They were designed with the knowledge that changes in atmospheric pressure results in changing weather patterns. Although anyone can use a barometer, they are widely used by meteorologists to predict short-term weather changes in a specific area.

High-pressure and low-pressure:

High atmospheric pressure usually means that we will recieve 'good weather' and calm conditions including, clear skies, light winds often just a gentle breeze, with no chance of rainfall.

Low atmospheric pressure indicates that skies will become cloudy, with a high chance of rainfall and windy conditions.

Atmospheric pressure is measured in the unit ‘hPa’ (hectopascal), it’s important when checking your barometer for pressure measurements you are aware of both high and low-pressure unit ranges. The needle covers a range between 960 and 1060 hPa, if the needle approaches and exceeds 1015hPa this indicates that atmospheric pressure is high and good weather is guaranteed. However, if the needle begins to drop rapidly below 1000hPa or exceeds 980hPa, this means a thunderstorm is set to strike. A calmer fall in atmospheric pressure simply indicates that cloudier and potentially rainy conditions are set to arrive.

Barometers:

Barometer types to choose from are either Mercury barometers or Aneroid barometers, at ClimeMET we provide a stylish range of traditional and contemporary aneroid barometers, measuring atmospheric pressure in either mmHg or mb. Suitable for use in both your home and garden, perfect for avid weather watchers and those worried about getting caught out in the rain!

The 'Constable' Banjo Barometer CM4280

An aneroid barometer has a sealed metal chamber with a flexible capsule inside that expands and contracts depending on the atmospheric pressure, the measurements are then displayed by a needle that is attached to the hidden capsule and adjusts accordingly to the pressure-volume.

Mercury barometers are the oldest style of barometer, They involve a glass tube with a small amount of mercury liquid inside that rises and falls within the tube depending on the atmospheric pressure.

Setting up your barometer:

Getting started:

When your barometer arrives, it's time to unbox and decide where to mount your dial. It's recommended that you position your dial in an undisturbed area away from direct sunlight and any sources of heat, for most accurate readings.

Setting up:

Firstly, you must establish the current air pressure readings for your location, to do this please visit: www.bbc.co.uk/weather

Next, adjust the needle on the face of the dial to your current air pressure readings by turning the small cog at the back of your barometer dial, TOP TIP: make sure you don't over tighten as this can cause damage to the dial mechanism.

Hang your barometer in your desired location, using the keyhole fitting at the back, once your barometer has been mounted wait a couple of days before taking any recordings, ensuring your barometer has had sufficient time to adjust to its surrounding air pressure.

How to record:

You can read atmospheric pressure in real time using both measurements Hg and hPa.

If the needle has moved clockwise this indicates rising pressure, therefore forecasting improving weather.

However, if the needle has shifted anti-clockwise this indicates decreasing pressure, forecasting deteriorating weather, such as strong winds, cloudy conditions and rainfall.

TOP TIP: To help monitor changes in atmospheric pressure, use the settable pressure pointer. The pointer is controlled by the knob at the center of the dial face. Move your pointer until it rests over the internal needle. The next time you read your barometer, it will be clear if there has been any change in pressure as highlighted by the distance between the needle and the pointer.

Maintenance:

Although our dials are low maintenance, there are some factors to consider, if you would like you dial engraved this would render the product suitable for indoor usage only to protect the quality of the engravement.

Unlike our standard barometer dial, the banjo barometers are suitable for indoor use only, to preserve the finish of the wood.

Lastly, if you are using the pressure pointer for accurate readings the pointer will need to be readjusted after each reading.

FAQs:

What are the different types of barometers?
The main types of barometers are:

Mercury Barometer: Uses a column of mercury to measure pressure.
Aneroid Barometer: Uses a flexible metal capsule to measure pressure.

How do I read an aneroid barometer?
Read the position of the needle on the dial. The dial shows atmospheric pressure directly, usually in millibars (mb) or inches of mercury (inHg)

Can a barometer be used indoors?
Yes it can, however, ensure you place it away from any draft, direct sunlight, or manmade heat sources for the most accurate readings.

Can a barometer predict long-term weather?
Barometers are mainly used for predicting short-term weather, over the next 48 hours, they indicate immediate changes in weather rather than long-term predictions.

How do I set up my barometer?
Firstly, google the current atmospheric pressure using reliable sources such as the MET Office.
On the back of the barometer adjust the screw either + or – (whichever is necessary) so the needle at the front displays the correct reading.