The powerful windstorm, Storm Ciaran, which battered the United Kingdom in early November 2023, did more than just bring 70 mph gusts and widespread flooding. A new study published in the Royal Meteorological Society reveals that the record low pressure caused by the storm actually lowered the boiling point of water, potentially affecting millions of tea drinkers.
Air pressure plays a crucial role in determining the boiling point of liquids. A liquid boils when its vapor pressure equals the surrounding air pressure. Therefore, lower air pressure results in a lower boiling point. Researchers at the University of Reading seized this opportunity to study Ciaran’s impact.
Utilizing a sensitive barometer at the university’s atmospheric observatory and data from other local meteorological stations, the researchers precisely measured the pressure drop during the storm. To demonstrate the real-world effect, they employed a simple kettle and thermometer. At the storm’s peak, they observed water boiling at 98 degrees Celsius, a significant two-degree drop from the standard 100 degrees.
While this minor temperature difference may not have noticeably reduced energy consumption for boiling water, the researchers identified a significant impact on a cherished British tradition: tea. The optimal temperature for extracting tannins, the compounds responsible for tea’s distinctive flavor, is 100 degrees Celsius.
Ciaran’s influence on the boiling point meant that tea brewed during the storm’s peak, particularly in London and southeastern England, likely fell short of this ideal temperature. The study estimates that this could have affected approximately 20 million people, resulting in a less flavorful cup of tea.
“Like many Britons, I need my morning cup of tea,” commented study co-author Giles Harrison in a press release. He added, “Although I know that the boiling point of water varies with atmospheric pressure, I wasn’t expecting a storm to take the boiling water temperature outside the recommended range for brewing decent tea. Weather can have subtle effects.” The study highlights the unexpected ways extreme weather events can influence everyday phenomena.
