Definition
An instrument that continuously records atmospheric pressure over time. It uses a pressure-sensitive element (typically an aneroid capsule) linked to a pen that traces pressure changes onto a paper chart wrapped around a slowly rotating drum, producing a visible record of pressure trends across hours or days.
Plain English
A device that draws a line on a chart showing how air pressure rises and falls throughout the day.
Context Anchor
Seen in weather observing stations and weather study when reviewing pressure trends before or during flight planning.
Derivation
From Greek baros meaning 'weight' and graph meaning 'to write'. Literally a 'weight writer' — it writes down the weight of the atmosphere as pressure changes.
Why Pilots Care
A barograph shows the trend of pressure change, not just a single reading. A steadily falling trace warns of approaching low pressure and deteriorating weather; a rising trace suggests improving conditions. Glider pilots also use sealed barographs to record altitude profiles for badge and record flights.
Example Sentence 1
The forecaster checked the barograph and saw a sharp drop in pressure over the past three hours, suggesting a fast-moving front.
Example Sentence 2
Preflight review of the barograph helped verify the reported altimeter setting.