The weather glass: A useful tool for weather observation
Despite modern and digital weather devices, what I’ll call more old-school weather tools still serve a purpose.
Before the advance of weather forecasting, a weather glass was quite common. It remains a staple in some homes as a useful tool to provide insights about our changing weather.
Dutch nobleman Gheijsbrecht de Donckere is credited with developing the weather glass barometer in the 16th century, and according to the Cooperative Institute for Research in the Atmosphere, it’s believed Pilgrims brought the weather glass to North America in the 1620s.
How does a weather glass barometer work? It’s often pear-shaped with a flat back, but some are globe shaped, all with an open spout. Water with coloured dye — often blue or red is filled into the glass so it’s noticeable and easy to observe.
The void created above the water inside the glass exerts the pressure of the air when filled, while the spout is exposed to changing air pressure.
As atmospheric pressure changes, so too does the water level in the spout — rising with low-pressure, or bad weather, and dropping with high-pressure, or fair weather.
Because liquid can expand and contract with changes in temperature, it’s recommended that a weather glass be mounted out of direct sunlight where there are minimal changes in temperature.
The weather glass became a popular tool with fishermen and farmers thanks to its inexpensive and simple design, but above all, its signal of changing weather conditions, whether on a broad or localized scale.
While less common now — often decorative, people still use them for observation into our weather.
Despite not being a tool for exact air pressure measurements, a weather glass remains a useful indicator of overall changes in atmospheric pressure.