Barometric Pressure

Definition

Barometric pressure is the weight of the atmosphere above a specific point, usually measured in millibars (mb) or inches of mercury (inHg). This pressure decreases with altitude, affecting atmospheric density and temperature profiles, and plays a crucial role in determining weather patterns and climate conditions. Understanding barometric pressure helps explain how the atmosphere is structured vertically and how air behaves in different layers.

5 Must Know Facts For Your Next Test

1. Barometric pressure typically decreases by about 12 hPa for every 100 meters of elevation gained.
2. High-pressure systems are generally associated with clear skies and stable weather, while low-pressure systems can lead to clouds and precipitation.
3. The average sea-level pressure is around 1013.25 hPa (or 29.92 inHg), which is used as a reference point for weather forecasting.
4. Changes in barometric pressure can signal incoming weather changes, such as approaching storms or fair weather conditions.
5. Barometric pressure can vary widely due to temperature changes, humidity levels, and geographic location, influencing local climate characteristics.

Review Questions

• How does barometric pressure influence atmospheric density and temperature profiles?
  • Barometric pressure directly impacts atmospheric density because as altitude increases, pressure decreases, leading to lower density of air. In temperature profiles, lower barometric pressure at higher altitudes typically results in cooler temperatures due to the expansion of air as it rises. This relationship helps to define the vertical structure of the atmosphere, where changes in pressure contribute to variations in temperature across different layers.
• Discuss the significance of barometric pressure in predicting weather patterns and understanding atmospheric layers.
  • Barometric pressure is a key indicator for meteorologists when predicting weather patterns. High-pressure systems are often linked to stable, clear conditions, while low-pressure systems indicate potential storms and precipitation. Additionally, understanding how barometric pressure changes with altitude helps define the structure of atmospheric layers, revealing how temperature and density vary within those layers and influencing overall climate behavior.
• Evaluate the impact of altitude on barometric pressure and how this relationship affects local climate and weather conditions.
  • As altitude increases, barometric pressure decreases due to the diminishing weight of the air above. This decline in pressure alters air density and temperature gradients, leading to significant climatic variations between lower elevations and mountainous regions. For example, higher altitudes tend to have cooler temperatures and potentially more precipitation as air rises and cools. This relationship is crucial for understanding local climates, as mountain ranges can create distinct weather patterns on their windward and leeward sides.

Related terms

Atmospheric Pressure: The force exerted by the weight of air above a given point, which decreases with increasing altitude.

Hydrostatic Balance: The state in which the upward pressure gradient force is balanced by the downward gravitational force in the atmosphere.

Isobar: A line on a weather map that connects points of equal barometric pressure, indicating areas of high and low pressure.