Air Pressure

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Air Pressure Noun

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[air presh-er]

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Air Pressure

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The force exerted by the weight of air over a unit of area, caused by gravity and air particle motion.

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Example: This image shows that air pressure is lower at high altitudes because there are fewer air molecules above, and higher at low altitudes where the column of air is heavier.

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Gravity Noun

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[grav-i-tee]

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Gravity

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The fundamental force that attracts objects with mass, pulling air particles toward Earth and giving air its weight.

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Example: This image shows an apple falling from a tree towards Isaac Newton, illustrating the concept that gravity is a force that pulls objects towards the Earth.

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Kinetic Energy Noun

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[ki-net-ik en-er-jee]

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Kinetic Energy

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The energy an object possesses due to its motion, which causes air particles to collide and exert pressure on surfaces.

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Example: Kinetic energy is the energy of motion, shown here as a soccer ball moving after being kicked. Its energy depends on its speed and mass.

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Mass Noun

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[mas]

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Mass

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The measure of the amount of matter in an object; air possesses mass, which is the reason it has weight.

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Example: This balance scale shows an apple has more mass than a 1-gram weight, demonstrating that mass is the amount of matter in an object.

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Altitude Noun

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[al-ti-tood]

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Altitude

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The height of an object or point in relation to sea level, where air pressure decreases as the altitude increases.

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Example: This diagram shows that as altitude increases from sea level to a mountain top, the air becomes less dense, causing air pressure to decrease.

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Density Noun

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[den-si-tee]

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Density

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The amount of mass per unit of volume; denser air has more particles, resulting in higher pressure near Earth's surface.

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Example: Air warmed by the land becomes less dense and rises, while cooler, denser air over the water sinks, creating air currents called thermals.

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Humidity Noun

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[hyoo-mid-i-tee]

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Humidity

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The concentration of water vapor present in the air; higher humidity can lead to lower air density and pressure.

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Example: As air rises, it cools, causing its relative humidity to increase. When humidity reaches 100%, the water vapor condenses to form a cloud.

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High-Pressure Zone Noun

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[hy presh-er zohn]

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High-Pressure Zone

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A region where atmospheric pressure is greater than its surroundings, often associated with sinking cool air and clear weather.

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Example: This diagram shows cool, dense air sinking towards the Earth's surface. This downward movement creates a high-pressure zone, which typically results in clear skies.

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Low-Pressure Zone Noun

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[loh presh-er zohn]

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Low-Pressure Zone

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A region where atmospheric pressure is lower than its surroundings, often associated with rising warm air and stormy weather.

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Example: This diagram shows a low-pressure zone, where air pressure is lowest at the center and increases in the surrounding areas.

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Barometer Noun

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[buh-rom-i-ter]

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Barometer

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A scientific instrument specifically designed and used for measuring atmospheric pressure to help forecast weather changes.

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Example: This diagram shows a mercury barometer, where the weight of the air (atmospheric pressure) pushes on the mercury, balancing and supporting a column inside the tube.