Air Pressure

Air pressure is the force exerted onto a surface by the weight of the air above that surface in the Earth's atmosphere. It is the result of the mass of air molecules pressing down on an area. Air pressure is an important concept in understanding weather patterns and phenomena.

Factors Affecting Air Pressure

Several factors can affect air pressure, including:

1. Altitude: Air pressure decreases with increasing altitude. As you go higher in the atmosphere, there are fewer air molecules above you, so the pressure decreases.
2. Temperature: Warmer air is less dense and exerts lower pressure, while cooler air is denser and exerts higher pressure.
3. Humidity: Moist air is less dense than dry air, so it exerts lower pressure.
4. Weather Systems: High-pressure systems are associated with clear skies and calm weather, while low-pressure systems are associated with stormy weather.

Measuring Air Pressure

Air pressure is commonly measured using a barometer. The two main types of barometers are mercury barometers and aneroid barometers. Mercury barometers use the height of a mercury column to measure pressure, while aneroid barometers use a flexible metal box to detect pressure changes.

Study Guide Questions

1. What is air pressure and how is it formed?
2. Explain how altitude affects air pressure.
3. How does temperature affect air pressure?
4. Describe the relationship between humidity and air pressure.
5. What are the characteristics of high-pressure and low-pressure weather systems?
6. What instruments are used to measure air pressure?
7. Compare and contrast mercury barometers and aneroid barometers.