Here's how it works:

* Thin Metal Cells: Barometers use a sealed metal container called an aneroid cell. Inside the cell, the air pressure is partially removed, creating a vacuum.

* Air Pressure Changes: As air pressure outside the cell increases, it pushes on the cell, causing it to compress. Conversely, when air pressure decreases, the cell expands.

* Dial or Digital Face: The compression or expansion of the aneroid cell is connected to a dial or digital display that shows the air pressure reading.

Let me know if you have more questions!