Barometer
A barometer is a type of manometer that specifically measures a pressure relative to a prevailing atmospheric pressure (manometers more specifically measure pressure differences). Air in the atmosphere has a weight which presses against all surfaces on the earth as gravity pulls it inward, barometers measure this pressure. Different barometer designs exist (similarly with manometer designs), essentially there are those containing a fluid (mostly mercury) in a closed or open tube design, those without a fluid, using mechanical parts called an aneroid barometer and contemporary or digital barometers.
Barometers measure atmospheric pressure, the units were originally referred to as atmospheres, relating to a unit of air pressure at sea level at a temperature of 15 degrees C, later this was defined as 1.01325 x 105 pascals. Today this is often referred to as bar which is simply a pressure unit, and defined as 100 kilo-pascals. So one atmosphere (atm) is almost the same as one bar, but not quite, more specifically 1 atm is equal to 1.01325 bar. These devices often found outside windows in homes, used to measure the outside air pressure to assist in weather predictions, as rising air pressure indicates a good weather forecast whilst falling pressure might forecast rain or bad weather.
The first fluid barometer was invented by Italian physicist Evangelista Torricelli in 1643, it contained water and was over 10 metres in height. Water is relatively light in weight, the tall tube compensated for the heavier weight of atmospheric pressure, which was later redesigned with mercury as it is over ten times heavier and allowed for a much shorter tube. The design contains a single tube sitting in a pool of mercury, as atmospheric pressure applies a for to the pool the measure rises in the tube. A cistern barometer patented by Daniel Quare in 1695 was a sealed design so prevented spillage of mercury (a toxic substance now banned) and allowed easier transportation. The angle or diagonal barometer expanded the barometer scale allowing for better readings.
In 1844, Lucien Vidie a French lawyer and engineer (1805-1866) successfully produced a metallic barometer that used springs to measure atmospheric pressure known as an aneroid barometer. These devices have a sealed metal chamber which expands and contracts, depending on the atmospheric pressure surrounding it around it. A series of rods and cogs measure the mechanical movement of the chamber as it expands or contracts, to a scale aligned with atmospheres or bars. A barograph is a type of aneroid barometer linked to a pen arm that continually records the vertical displacement of the chamber over time creating a graphical record of atmospheric pressure changes.
Modern digital barometers use capacitive or piezo-resistive micro-electromechanical (MEMs) sensors to measure pressure, these combine electronic and mechanical elements in small integrated circuits (IC) to sense pressure differences and record them digitally.
[edit] Related articles on Designing Buildings
- Weather.
- Adverse weather.
- Balometer.
- Climate.
- Cold stress.
- Drought.
- Exceptionally adverse weather.
- Excess cold.
- Extraordinary weather event.
- Extreme weather.
- Extreme weather event.
- Fire weather.
- Flood.
- Heat wave.
- Hurricane.
- Monsoon.
- Overheating.
- Solar radiation.
- Rainfall.
- Thermal comfort.
- Tropical cyclone.
- Wind.
Featured articles and news
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
CIOB Construction Manager of the Year 2025
Just one of the winners at the CIOB Awards 2025.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.
Construction Products Reform Green Paper and Consultation
Still time to respond as consultation closes on 21 May 2025.
Resilient façade systems for smog reduction in Shanghai
A technical approach using computer simulation and analysis of solar radiation, wind patterns, and ventilation.