The atmospheric pressure is the weight of the column of air over any point or place on the earth and is therefore the weight per unit area. In simpler words it is the force exerted by the air on us.
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Some principles and concepts about atmospheric pressure.
The higher the height, the lower the atmospheric pressure and the lower the height and the closer it gets to sea level, the greater the pressure.
Apparatus for measuring atmospheric pressure:
The atmospheric pressure is measured with a device called a barometer, which was created in 1643 by the physicist and mathematician Evangelista Torricelli.
The mercury barometer(Torricelli's invention) consists of a 850 mm high glass tube, closed at the top and open at the bottom. This tube is filled with mercury and is placed over an open container also filled with mercury. At sea level, the mercury level inside the tube drops to a height of about 760 mm, leaving a vacuum at the top. This allowed us to determine that the average atmospheric pressure at sea level is 760 millimeters of mercury (760 mmHg).
The aneroid barometer does not carry mercury and is the one used in navigation. It consists of a metal box, also called vidi capsule, in which the vacuum has been partially made. This box contracts with the increase or decrease of the pressure exerted on it, transmitting its movements to a needle that is what indicates the value of the atmospheric pressure on a graduated surface.
It is not the precision of the measurement of the barometer that is the most important to be able to predict the time, but the variation of pressure that occurs over the course of time. To measure this pressure variation in relation to time, a device called barograph is used. The barograph measures the pressure and at the same time registers its fluctuations by making a graph over a period of time.
We have mentioned, what is the atmospheric pressure and how is it measured ?, but why do we want to know that?
The proportion of oxygen in the air is constant (21%) as that of the other gases that make up the atmosphere and is not reduced to great heights, but the partial pressure of oxygen decreases, with the consequence that the number of oxygen molecules decreases per cubic meter of air. This decrease in the partial pressure of oxygen, by reducing the transfer of gas from the inspired air to the blood, causes several immediate reactions in the body:
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- Increases the speed of breathing and the volume of inspired air producing a hyperventilation.
- The heart rate and the outflow of blood are increased.
- The body produces more red blood cells and hemoglobin to improve the oxygen transport capacity of the blood. The increase in the number of red blood cells requires 38 weeks, and the increase in hemoglobin occurs in 2 or 3 months.
People who have some alteration of the respiratory and vascular systems should not live at high altitudes, because they are unable to support the adaptations that are required.
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What else can we learn?
Regulates the masses of cold and warm air in large areas or locally, so a mass of high pressure brings as a consequence, little rain or very scarce and distanced, which implies that you have to induce irrigation artificially, vice versa with low pressures.
It has a great influence on the feeding of animals, because if you have high pressures, it means little rain, scarce food and slower recovery of the biomes, there is a shortage of water which forces the induction of drinking or migrate where this resource exists .
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In general, animals adapt to changes in seasonal atmospheric pressures, travel and reproduce at the most favorable periods for breeding success.
In agricultural activities, atmospheric pressure only influences the regulation of rainfall. Agricultural constraints in high areas are associated with low temperatures, not at low atmospheric pressures.
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Living beings are adapted to live in certain ecological niches in which pressure is a determining factor. Besides the pressure is the origin of the winds, the atmospheric pressure goes hand in hand with the height above sea level because of this, some species, above all, forests do not grow at sea level and vice versa.
References:
-http://acmg.seas.harvard.edu/people/faculty/djj/book/bookchap2.html
-https://extension.illinois.edu/treehouse/airpressure.cfm?Slide=3
-https://science.howstuffworks.com/nature/climate-weather/atmospheric/barometer.htm
-http://blog.teachersource.com/2014/02/01/examples-of-air-pressure-in-everyday-life/
-https://www.met.ie/climate-ireland/pressure.asp
-http://www.physics.org/facts/air-atmospheric-pressure.asp
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Nice one!
I was learning this week about the pressure and where it comes from in the world. Studying nautical science we mainly look at typhoons, hurricanes ed. It's nice to logically draw the path to the things on the main land, thank you!
Thank you for your comment. Atmospheric pressure is one of those things that people don't notice but it is there all the time; i'm glad that you learned about it!