How a Mercury Barometer Measures Atmospheric Pressure #23286 (License: Personal Use)

This diagram illustrates a traditional mercury barometer, where atmospheric pressure acting on the mercury reservoir (point B) supports a column of mercury rising inside a sealed glass tube. The space above the mercury column (point A) is a vacuum, allowing precise measurement of air pressure based on the height of the mercury column. The red arrows indicate equal atmospheric pressure applied uniformly on the reservoir surface.

Used in educational physics or meteorology content to explain atmospheric pressure measurement; matches user intent for understanding barometric principles, historical instruments, or weather science fundamentals.