Know More on Atmospheric Pressure

Whether you realise it or not, atmospheric pressure impacts your daily life. Atmospheric pressure affects weather patterns and forecasts all across the world. High atmospheric pressure can result in colder temperatures and clear skies, whereas low atmospheric pressure frequently results in warmer temperatures and clouds, potentially with rain.

But what is atmospheric pressure, and why does it fluctuate? You will better comprehend how to measure atmospheric pressure once you have grasped the fundamentals. Continue reading to find out more.

What is atmospheric pressure?

The overall force exerted on a surface by the air above it due to the Earth’s gravity forces is referred to as atmospheric pressure. As it is measured with a barometer, atmospheric pressure is also known as barometric pressure. A rising barometer implies that atmospheric pressure is increasing, whereas a falling barometer indicates that atmospheric pressure is decreasing.

In a nutshell, atmospheric pressure is created by the air that surrounds the Earth, and the combined weight of air molecules defines this pressure. Air molecules at higher altitudes have fewer molecules pressing down on them from above, resulting in lower pressure. On the other hand, lower molecules are subjected to more force or pressure from molecules heaped on top of them, and are more closely packed together, leading to greater pressure.

What is the SI unit of atmospheric pressure?

The force applied to a surface per unit area is known as pressure. Pressure is measured in several units. The weight of the atmosphere causes atmospheric pressure, which is measured in units other than pascal.

The pascal is the SI unit of pressure (Pa). 1 Pa equals 1 newton per square metre. Atmospheric pressure is measured in atm, which is pronounced as atmospheres in SI. 

The value of normal atmospheric pressure is 101325.

Therefore, 1 Atmospheric Pressure = 101325 Pascal

Highs and lows

So, what is the relationship between atmospheric pressure and everyday weather patterns? You have probably seen weather forecasts on television, with the on-camera weathercaster referring to high and low-pressure systems. What is the big deal about that?

In a nutshell, the heat of the sun fluctuates throughout the Earth every day. Temperatures vary globally due to unequal solar heating; the air near the equator is substantially warmer than at the poles. Warm, light air rises and spreads to the poles, while colder, heavier air sinks to the equator.

Moreover, due to low atmospheric pressure, the rate of transpiration will increase. If the atmospheric pressure is low, air (which includes water) will move out of the plant as it moves from high to low pressure, increasing transpiration. If other environmental conditions are not restricted, plants growing at high elevations have much lower atmospheric pressures, resulting in significantly higher rates of transpiration.

After knowing that the rate of transpiration will increase due to low atmospheric pressure, it is time to move ahead with some other important terms, such as the reason behind atmospheric pressure.

What causes a change in atmospheric pressure?

The causes of change in atmospheric pressure are as follows:

Density

The barometric pressure is affected by the density of a mass of air. There are more air molecules applying pressure on a certain place on Earth if the mass of air over that spot is denser. Due to this, the atmospheric pressure is higher. If fewer air molecules apply pressure on the same spot, the mass of air will be less dense, and the barometric pressure will be lower.

Gravity

Gravity pulls air molecules to the ground, as it does to all other molecules. The force of gravity affects the pressure that molecules exert on the Earth. The barometric pressure on the moon, for example, would be lower than the barometric pressure on Earth due to the moon’s lower gravity.

Altitude

Because altitude has an effect on temperature, it has an indirect effect on barometric pressure. Since the temperatures in the mountains are colder than those at the beach, the mountains have a higher average barometric pressure. Furthermore, due to a significant increase in barometric pressure, flying in an aeroplane may cause your ears to pop. The plane travels through chilly air at high altitudes, which causes this increase.

Temperature

As hot air is less dense than cool air, it rises, and cool air falls. This can be understood by considering how molecules move in hot and cold air. Because molecules in hot air travel swiftly, they tend to bounce off of one another and drift apart, resulting in a less dense air mass. Because molecules travel more slowly in cold air, they tend to stick together, resulting in a denser mass of air.

How to read a barometer?

If you know what different atmospheric pressure numbers mean, reading a barometer is simple. Interpret your barometer readings as follows to better understand how atmospheric pressure is changing.

General interpretations

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

 Specific interpretations

•   A barometric pressure reading of more than 30.20 inHg is considered high, and it is related to a clear sky and calm weather.
•   A normal barometric pressure reading is between 29.80 and 30.20 inHg, and normal pressure is associated with stable weather.
•   Low pressure is defined as a barometric pressure reading of less than 29.80 inHg, and it is related to warm air and rainstorms.

Conclusion

Finally, atmospheric pressure is the finest if not the most essential indication of current and evolving weather conditions. Weather forecasters only need to know the atmospheric pressure at a specific location to predict the weather. In most cases, weather forecasts are defined by predictions of the pressure system that will affect a certain location.

In this article, we learned what atmospheric pressure is, what causes it, how due to low atmospheric pressure, the rate of transpiration increases, and how we can interpret barometer readings.