Barometer

Definition

A barometer is an instrument used to measure atmospheric pressure. It plays a vital role in understanding weather patterns and predicting changes in the atmosphere, as fluctuations in atmospheric pressure can indicate upcoming weather changes, such as storms or clear skies. Barometers can be classified into two main types: mercury barometers and aneroid barometers, each having distinct mechanisms for measuring pressure.

5 Must Know Facts For Your Next Test

1. Mercury barometers use a column of mercury to measure pressure, where the height of the mercury column indicates the atmospheric pressure.
2. Aneroid barometers use a flexible metal chamber that expands or contracts with changes in pressure, providing a reading without liquid.
3. As altitude increases, atmospheric pressure decreases; therefore, barometers must be calibrated for accurate readings at different elevations.
4. Barometric pressure is typically reported in inches of mercury (inHg) or millibars (mb), with standard sea-level pressure defined as 29.92 inHg or 1013.25 mb.
5. Changes in barometric pressure are crucial for meteorologists to forecast weather events, as rapid drops may indicate approaching storms or severe weather.

Review Questions

• How do changes in atmospheric pressure as measured by a barometer relate to weather predictions?
  • Changes in atmospheric pressure are closely linked to weather conditions. A falling barometer reading generally indicates that atmospheric pressure is decreasing, which is often associated with approaching storms or inclement weather. Conversely, a rising barometer suggests improving weather conditions with clear skies. Meteorologists use these readings to make informed predictions about future weather patterns.
• Discuss the differences between mercury and aneroid barometers and their applications in measuring atmospheric pressure.
  • Mercury barometers use a column of mercury to measure atmospheric pressure, making them highly accurate but heavy and delicate. They require careful handling and calibration. On the other hand, aneroid barometers employ a flexible metal chamber to measure changes in pressure without using liquid, making them more portable and easier to use. Both types are essential for understanding atmospheric conditions, but their applications may differ based on the need for precision or convenience.
• Evaluate the significance of altitude on barometric readings and its implications for meteorological practices.
  • Altitude significantly impacts barometric readings since atmospheric pressure decreases with elevation. This means that a barometer calibrated at sea level will not provide accurate readings at higher altitudes unless adjustments are made. Meteorologists account for altitude when interpreting pressure data, as accurate assessments are crucial for weather forecasting and understanding local climate conditions. The effects of altitude are particularly important when comparing data from different geographic locations and ensuring reliable meteorological analysis.

Related terms

Atmospheric Pressure: The force exerted by the weight of air above a given point, typically measured in units like Pascals or millibars.

Weather Front: A boundary between two different air masses, which can cause changes in weather conditions, often indicated by shifts in barometric pressure.

Altitude:

The height of an object or point in relation to sea level, which affects atmospheric pressure and readings on a barometer.