Understanding and Measuring Air Pressure

• Meteorology studies weather, which is influenced by various Earth properties, including air pressure.
• Air pressure is the force exerted by the weight of air above a specific location.
• Higher air pressure occurs with more air particles above a location; lower air pressure occurs with fewer air particles.
• Air pressure is higher at lower elevations (e.g., beach) compared to higher elevations (e.g., mountains).
• High and low-pressure systems form globally due to air circulation caused by Earth's rotation.

Measuring Air Pressure

• Air pressure is commonly measured using a barometer.
• Three main types of barometers exist: mercury, aneroid, and digital.
• Mercury barometers use the rise and fall of mercury in a glass tube to measure air pressure changes.
• Air pressure is often measured in millimeters of mercury (mmHg).
• Millimeters of mercury can then be converted to atmospheres (atm), Pascals (Pa), or bars.
• Aneroid barometers use metal parts instead of mercury.
• Changes in air pressure move a needle to indicate atmospheres or bars.
• Digital barometers use changes in rubber pieces to measure air pressure.
• Digital barometer readings can be stored to track air pressure over time.
• Digital barometers are often included in smartphones.
• Combining barometers with other tools improves navigation systems and weather predictions.

High-Pressure Systems

• Also known as anticyclones, they occur when air pressure is higher than surrounding areas.
• Rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere due to the Coriolis Effect.
• Form when air cools, becoming denser and sinking towards the Earth's surface.
• Sinking air increases pressure readings.

High-Pressure System Measurements

• Typically have barometer readings above 1013 millibars (mb) up to 1050 mb.
• Air pressure increases towards the center of the high-pressure system.
• The center has higher air pressure than surrounding areas.

Related Weather and Air Movement

• Usually bring clear, dry weather with minimal wind due to small pressure differences.
• Can increase the risk of sunburn and dehydration.

High-Pressure System Hazards

• Heat waves, periods of above-average temperatures lasting 2-5 days can occur
• Heat waves lead to heat exhaustion and heatstroke.
• Increased air conditioning use during heat waves strains energy resources.
• Extended high-pressure systems can cause droughts by increasing evaporation and preventing rainfall.
• Droughts negatively impact plants, animals, ecosystems, and urban communities, affecting irrigation.

Low-Pressure Systems

• Also known as cyclones, they occur when air pressure is lower than surrounding areas.
• Rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere due to the Coriolis Effect.
• Air rises away from the surface because warm air is less dense than cool air.
• Rising air decreases pressure readings.

Low-Pressure System Measurements

• Typically have barometer readings below 1013mb down to 980mb.
• Air pressure below 980mb increases the risk of extreme weather.
• Air pressure decreases towards the center of the low-pressure system.
• The center has lower air pressure than surrounding areas.

Related Weather and Air Movement

• Bring cooler temperatures.
• Cause cloud formation and often rain due to condensation.
• Important for watering crops and balancing air temperatures.

Low-Pressure System Hazards

• Prolonged low-pressure systems can cause major flooding.
• Flooding impacts homes, businesses, and ecosystems.
• Short, powerful downpours from low-pressure systems can cause flash floods.
• Low-pressure systems with very low barometric pressure create fast winds, potentially forming tornadoes.
• Tornadoes are destructive to both human developments and ecosystems.
• Hurricanes develop when low-pressure systems are supplied with extra water from the ocean.
• Hurricanes have high winds and flooding, and can change ecosystems.

Explore the concept of air pressure in meteorology, its correlation with elevation, and the formation of high and low-pressure systems. Learn about different types of barometers, including mercury, aneroid, and digital, used to measure air pressure. Understand the units of measurement such as mmHg, atm, Pascals, and bars.