Which of the following choices represents a long-term recording of atmospheric pressure?

A barograph is a device specifically designed to record atmospheric pressure over an extended period. It operates using a stylus that writes on a rotating drum, which is connected to a mechanism that responds to changes in air pressure. As atmospheric pressure changes, the barograph produces a continuous paper record, allowing for the monitoring of pressure trends over time. This long-term recording capability makes it a valuable tool for meteorologists and researchers in observing and analyzing pressure patterns related to weather systems.

In contrast, the other instruments serve different purposes. An anemometer measures wind speed, an altimeter measures altitude based on atmospheric pressure but typically does not record pressure trends, and a hygrometer measures humidity levels in the air. None of these devices are designed for long-term atmospheric pressure recording.