Pressure tendency, the change in atmospheric pressure over a specific period, is measured by observing and recording barometric changes. This can be done using various instruments and methods.
Here's a breakdown of common methods:
- Digital Electronic Barometers: Many modern digital barometers automatically calculate and display the pressure tendency alongside the current pressure reading. They use internal sensors to continuously monitor pressure changes over a predefined period (e.g., 3 hours).
- Barographs: A barograph is an analog instrument that continuously records atmospheric pressure on a rotating drum. The resulting chart (barogram) visually represents the pressure changes over time, allowing you to directly observe and measure the pressure tendency by analyzing the slope of the recorded line.
- Manual Barometer Readings: You can manually determine pressure tendency by taking regular readings from a barometer corrected to station level (taking into account altitude) and calculating the difference between the readings over a specific time interval. This requires precise instruments and consistent observation.
Methods Summarized:
| Method | Description | Advantages | Disadvantages |
|---|---|---|---|
| Digital Electronic Barometer | Uses electronic sensors to continuously monitor and display pressure and tendency. | Automated, convenient, often includes trend indicators. | Relies on battery power, can be susceptible to electronic malfunctions. |
| Barograph | Mechanically records atmospheric pressure on a chart. | Provides a visual record of pressure changes over time, doesn't require power. | Requires maintenance, less precise than digital instruments, more space-consuming. |
| Manual Readings | Taking regular barometer readings and calculating the pressure difference over time. | Can be done with a simple barometer. | Time-consuming, requires careful observation and correction, prone to human error. |
In summary, pressure tendency is measured by tracking changes in atmospheric pressure, which can be achieved through digital displays, visual records from barographs, or manual calculations from barometer readings.
