Atmospheric pressure and its effects

Atmospheric pressure is an interesting concept in physics that affects our everyday lives, even if we don't always notice it. In this explainer, let's learn what atmospheric pressure is, how it's measured, and what effects it has on us and the environment around us.

What is atmospheric pressure?

Atmospheric pressure is the force exerted by the weight of the air on us. Imagine that the Earth is covered by a blanket of air called the "atmosphere." This atmosphere is made up of nitrogen, oxygen, carbon dioxide, and other gases. The weight of these gases pushes down on everything on the Earth's surface, creating atmospheric pressure.

Let's visualise this with an example. Imagine a stack of pillows. The weight of the pillows placed on top pushes the pillows placed below downwards. Similarly, air molecules in the atmosphere pile up on each other, exerting downward pressure due to gravity, and this creates atmospheric pressure.

Measuring atmospheric pressure

To measure atmospheric pressure, scientists use an instrument called a "barometer". The barometer is an important instrument that tells us the pressure of the atmosphere at any place and time.

Types of barometers

There are different types of barometers, such as mercury barometer and aneroid barometer.

• Mercury barometer: This barometer uses a column of mercury in a glass tube. When atmospheric pressure changes, the mercury level rises or falls.

          Atmospheric Pressure (in mmHg) = Height of Mercury Column (in mm)
        Atmospheric Pressure (in mmHg) = Height of Mercury Column (in mm)
    

• Aneroid barometer: This uses a small, flexible metal box called an "aneroid cell." As atmospheric pressure changes, the box expands or contracts, and this motion is converted into a pressure reading.

Effects of atmospheric pressure

Atmospheric pressure has important effects that affect various aspects of life and the environment. Let's explore some of the major effects of atmospheric pressure.

Breathing and altitude

Atmospheric pressure affects the amount of oxygen available in the air. At sea level, atmospheric pressure is high, which means there is more oxygen available to breathe. As we go higher, such as in the mountains, atmospheric pressure decreases, which means there is less oxygen.

This is why you may have difficulty breathing on very high mountains or why mountaineers carry oxygen tanks with them.

Weather patterns

Atmospheric pressure plays an important role in weather patterns. Changes in pressure can cause different weather conditions. High atmospheric pressure usually means clear and sunny weather, while low atmospheric pressure can cause clouds, rain and storms.

Boiling point of liquids

The boiling point of a liquid is the temperature at which it turns into vapor. Atmospheric pressure affects this boiling point. At higher altitudes with lower atmospheric pressure, liquids boil at lower temperatures.

For example, water boils at 100°C at sea level. On high mountains, it may boil at around 90°C due to the lower atmospheric pressure. This is why cooking food may take longer at higher altitudes.

Everyday examples

• Drinking through a straw: When you drink through a straw, you create less pressure inside your mouth. The atmospheric pressure outside pushes the liquid through the straw into your mouth.
• Suction cups: Suction cups stick to surfaces due to atmospheric pressure, creating a seal.
• Vacuum cleaners: These work by creating low pressure inside the cleaner. The atmospheric pressure then pushes the debris into the vacuum.

Sensing pressure changes

Pressure changes happen all the time, but understanding them can help us anticipate certain atmospheric conditions or prepare for activities that take place at different altitudes.

View atmospheric pressure changes as a simple graph, where the Y-axis is pressure and the X-axis is time:

Atmospheric pressure in science and technology

Atmospheric pressure is an important concept in many scientific fields and technologies. It helps meteorologists forecast the weather and pilots fly airplanes. Engineers design buildings to withstand changes in pressure.

Weather forecast

Meteorologists study atmospheric pressure to forecast the weather. By tracking changes in pressure, they can predict storms, rain, and even sunny days.

Aviation

Pilots must understand changes in atmospheric pressure to fly airplanes safely. Air pressure decreases with altitude, which affects the lift on an airplane's wings.

Conclusion

Atmospheric pressure is an integral part of life on Earth, affecting everything from the weather we experience to the way our bodies work. It's interesting to see how this pressure affects even the most mundane activities, highlighting the interconnected nature of science and our daily lives.

Understanding atmospheric pressure gives us a greater understanding of how this invisible force shapes our world, helps us in a variety of fields from meteorology to aviation, and affects ordinary daily activities.

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