Atmospheric Pressure

Whether you know it or not, atmospheric pressure is an important part of your daily life. Atmospheric pressure has an impact on weather patterns and forecasts globally although many people do not realise its importance. If you know the fundamentals, you will be able to understand exactly what atmospheric pressure is and how you can measure this using a barometer. 

What do you mean by the atmosphere? 

The gaseous layer that surrounds our planet from all sides is known as the atmosphere. The atmosphere stretches from the surface of the earth to as far as 10,000 kilometres (6214 miles). It also has the presence of air and gases. The atmosphere has 72% nitrogen and 21% oxygen, with a little amount of carbon dioxide, other elements, and substances.

Define Atmospheric Pressure?

The force that is exerted at any given point on the Earth’s surface by the weight of the air above that point is defined as the atmospheric pressure. In simple words, you can say atmospheric pressure is created by the air that surrounds the Earth. Whereas the pressure is defined by the combined weight of air molecules present in that layer.

Air molecules at higher altitudes have fewer molecules pressing down on them from above causing low pressure. Whereas, lower molecules have more force or pressure put on them by molecules heaped on top of them and are more closely packed together, creating high pressure.

The air is thinner and the pressure is lower when trekking on the mountains or flying high in an aeroplane. If you observe the sea levels, at a temperature of 59°F (15°C), the air pressure at sea level will equal one atmosphere (Atm). This atmospheric pressure can be taken as the reference point for estimating relative pressure.

Atmospheric pressure can be measured by an instrument called a barometer. As a barometer is used to measure atmospheric pressure it is sometimes known as barometric pressure. A rising barometer indicates that atmospheric pressure is increasing, whereas a falling barometer tells us that atmospheric pressure is decreasing.

How does atmospheric pressure change? 

The differences in air temperature above the earth can lead to changes in pressure and the temperature of an air mass is also due to location. For example, air pressure above oceans is usually cooler than air pressure above land. The wind is created by temperature differences in the air, which is due to the formation of pressure systems. Pressure systems are moved by the wind, and when they pass through mountains, oceans, and other places, they tend to change.

Blaise Pascal who was a French scientist and philosopher created this system where when the air pressure drops with altitude or that pressure changes at ground level, this system can describe how your day will be. Today this scientific innovation helps to predict the weather.  

To determine the projected conditions for specific places, scientists often refer to high- or low-pressure areas moving toward such regions. When air cools as it rises in low-pressure systems, it condenses into clouds and precipitation, resulting in storms. Whereas, if the air dips toward the Earth and warms in high-pressure systems, it produces dry and pleasant weather.

Is weather influenced by pressure changes?

Mercury barometer can help you predict weather conditions in the future. These calculations are based on reading air pressure. There are a few examples of how to read barometer readings: 

• The barometer reading will rise when the air is dry, cool, and pleasant.
• Generally, a rising barometer tells us that the weather is improving.
• Also, the decreasing barometer indicates that the weather is getting worse.
• When the air pressure suddenly lowers, it usually means a storm is approaching.
• There will most likely be no immediate change in the weather if air pressure remains constant.

How can a barometer provide you with the correct readings? 

If you can read various numbers, you can easily find what different atmospheric pressure numbers mean. And reading a barometer is no big deal.

• If the barometric pressure reading is more than 30.20 in Hg then the pressure is high – it means clear sky and calm weather.

• If the reading is greater than 30.20 inHg (102268.9 Pa or 1022.689 MB)

• Normal weather is expected to persist as pressure rises or remains stable.
• Weather is predicted as the pressure slowly decreases.
• Cloudy and warmer days due to rapidly dropping pressure.

Conclusion 

In this article, we have learnt what is atmospheric pressure, what is air pressure and what does mercury barometer do? Atmospheric pressure is one of the important aspects of our daily life. If we do not know how to determine atmospheric pressure we wouldn’t be able to predict whether or any unforeseen circumstance.