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How To Calculate Atmospheric Pressure — Reading Comprehension

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This audio-integrated reading passage, "The Pressure of Air: Calculating Atmospheric Pressure," explores the concept of atmospheric pressure and how it's calculated. It defines key terms like barometer and Pascals, and explains the factors that influence air pressure, such as altitude. Students will learn that atmospheric pressure is the force exerted by the weight of the air above us. The passage also touches on the simplified formula for pressure, P=ρ⋅g⋅h, and explains why our bodies are not crushed by this force. The information aligns with the NGSS Disciplinary Core Idea of PS1.A: Structure and Properties of Matter, as it discusses the properties of air and its effect on our environment. This resource is perfect for a middle school science lesson on the properties of matter and forces.

CONTENT PREVIEW

A picture of a barometer with two gauges, one showing high pressure and one showing low pressure. — A barometer measures atmospheric pressure.

Atmospheric pressure is the force of air pressing down on everything at Earth’s surface. Even though air is invisible, it has weight. This weight creates pressure, almost like a giant, invisible hand pushing down on us all the time.

Scientists measure atmospheric pressure to understand the weather and how high a place is above sea level. The main tool for this is called a barometer. There are two main types. A mercury barometer uses a glass tube filled with liquid mercury, a heavy, silvery metal. When air pressure rises, it pushes the mercury higher in the tube. When pressure drops, the mercury falls. An aneroid barometer uses a small metal box that squishes in or out as air pressure changes. Weather stations often use electronic sensors to measure pressure quickly and send data to computers.

Atmospheric pressure is measured in special units. One unit is inches of mercury (inHg), which tells how high the pressure pushes the mercury in a barometer tube. At sea level, the average is about 29.92 inches of mercury. Scientists also use millibars (mb) or hectopascals (hPa), with average sea level pressure at about 1013 mb or hPa.

Pressure changes with altitude. At sea level, there is more air above, so pressure is higher. If you climb a mountain, there is less air above you, so the pressure becomes lower. For every 1,000 feet you go up, the pressure drops about 1 inch of mercury. It’s like weighing the invisible air above you—the higher you go, the less air there is to weigh!

Weather forecasters look at pressure to predict storms or nice weather. When pressure falls, it often means a storm is coming. When pressure rises, fair weather is likely. Pilots and hikers use special pressure tools called altimeters to know how high they are.

Interesting Fact: The highest air pressure ever recorded at sea level was over 32 inches of mercury, during a super cold winter in Siberia!

What does a barometer measure?

Air pressureWind speedTemperatureRainfall

What unit is used for air pressure?

Inches of mercuryCentimetersWattsLiters

What happens to pressure as you climb?

It dropsIt risesIt stays the sameIt disappears

Which tool do pilots use?

AltimeterThermometerRain gaugeWind vane

Pressure falls before a storm. True or false?

TrueFalse

Why do weather stations use electronic sensors?