Atmospheric pressure is commonly measured with a barometer. In a barometer, a column of mercury in a glass tube rises or falls as the weight of the atmosphere changes. Meteorologist s describe the atmospheric pressure by how high the mercury rises.
An atmosphere atm is a unit of measurement equal to the average air pressure at sea level at a temperature of 15 degrees Celsius 59 degrees Fahrenheit. One atmosphere is 1, millibar s, or millimeters Atmospheric pressure drops as altitude increases.
The atmospheric pressure on Denali, Alaska, is about half that of Honolulu, Hawai'i. Honolulu is a city at sea level. As the pressure decreases, the amount of oxygen available to breathe also decreases. At very high altitudes, atmospheric pressure and available oxygen get so low that people can become sick and even die.
Mountain climbers use bottled oxygen when they ascend very high peaks. They also take time to get used to the altitude because quickly moving from higher pressure to lower pressure can cause decompression sickness. Decompression sickness, also called "the bends", is also a problem for scuba divers who come to the surface too quickly. Aircraft create artificial pressure in the cabin so passengers remain comfortable while flying. Atmospheric pressure is an indicator of weather.
When a low-pressure system moves into an area, it usually leads to cloud iness, wind , and precipitation. High-pressure system s usually lead to fair, calm weather. As you go up in an airplane, the atmospheric pressure becomes lower than the pressure of the air inside your ears.
Your ears pop because they are trying to equalize, or match, the pressure. The same thing happens when the plane is on the way down and your ears have to adjust to a higher atmospheric pressure. Also called standard atmospheric pressure. Also known as DCS, divers disease, and the bends.
High-pressure systems are usually associated with clear weather. Low-pressure systems are often associated with storms. Sea level is determined by measurements taken over a year cycle. When body temperature rises well above or drops well below normal, certain proteins enzymes that facilitate chemical reactions lose their normal structure and their ability to function and the chemical reactions of metabolism cannot proceed.
That said, the body can respond effectively to short-term exposure to heat [link] or cold. As sweat evaporates from skin, it removes some thermal energy from the body, cooling it. Adequate water from the extracellular fluid in the body is necessary to produce sweat, so adequate fluid intake is essential to balance that loss during the sweat response.
Not surprisingly, the sweat response is much less effective in a humid environment because the air is already saturated with water. The body can also respond effectively to short-term exposure to cold. One response to cold is shivering, which is random muscle movement that generates heat. Another response is increased breakdown of stored energy to generate heat. When that energy reserve is depleted, however, and the core temperature begins to drop significantly, red blood cells will lose their ability to give up oxygen, denying the brain of this critical component of ATP production.
This lack of oxygen can cause confusion, lethargy, and eventually loss of consciousness and death. Even when core body temperature remains stable, however, tissues exposed to severe cold, especially the fingers and toes, can develop frostbite when blood flow to the extremities has been much reduced.
This form of tissue damage can be permanent and lead to gangrene, requiring amputation of the affected region. Controlled Hypothermia As you have learned, the body continuously engages in coordinated physiological processes to maintain a stable temperature.
In some cases, however, overriding this system can be useful, or even life-saving. Controlled hypothermia often is used, for example, during open-heart surgery because it decreases the metabolic needs of the brain, heart, and other organs, reducing the risk of damage to them. When controlled hypothermia is used clinically, the patient is given medication to prevent shivering. This very cold temperature helps the heart muscle to tolerate its lack of blood supply during the surgery.
Some emergency department physicians use controlled hypothermia to reduce damage to the heart in patients who have suffered a cardiac arrest. Pressure is a force exerted by a substance that is in contact with another substance. Although you may not perceive it, atmospheric pressure is constantly pressing down on your body. This pressure keeps gases within your body, such as the gaseous nitrogen in body fluids, dissolved.
The pressure of the nitrogen gas in your blood would be much higher than the pressure of nitrogen in the space surrounding your body. As a result, the nitrogen gas in your blood would expand, forming bubbles that could block blood vessels and even cause cells to break apart.
Atmospheric pressure does more than just keep blood gases dissolved. Your ability to breathe—that is, to take in oxygen and release carbon dioxide—also depends upon a precise atmospheric pressure. Altitude sickness occurs in part because the atmosphere at high altitudes exerts less pressure, reducing the exchange of these gases, and causing shortness of breath, confusion, headache, lethargy, and nausea.
Mountain climbers carry oxygen to reduce the effects of both low oxygen levels and low barometric pressure at higher altitudes [link]. Homeostatic Imbalances Decompression Sickness Decompression sickness DCS is a condition in which gases dissolved in the blood or in other body tissues are no longer dissolved following a reduction in pressure on the body.
This condition affects underwater divers who surface from a deep dive too quickly, and it can affect pilots flying at high altitudes in planes with unpressurized cabins. In all cases, DCS is brought about by a reduction in barometric pressure.
The very great pressures on divers in deep water are likewise from the weight of a column of water pressing down on the body. For divers, DCS occurs at normal barometric pressure at sea level , but it is brought on by the relatively rapid decrease of pressure as divers rise from the high pressure conditions of deep water to the now low, by comparison, pressure at sea level. Not surprisingly, diving in deep mountain lakes, where barometric pressure at the surface of the lake is less than that at sea level is more likely to result in DCS than diving in water at sea level.
In DCS, gases dissolved in the blood primarily nitrogen come rapidly out of solution, forming bubbles in the blood and in other body tissues. This occurs because when pressure of a gas over a liquid is decreased, the amount of gas that can remain dissolved in the liquid also is decreased. Beyond that, to give a precise answer as to where the atmosphere ultimately ends is well nigh impossible; somewhere between and miles comes an indeterminate region where the air gradually thins and ultimately merges into the vacuum of space.
So the layer of air that surrounds our atmosphere is not so huge after all. If a person were to climb a tall mountain, like Mauna Kea on the Big Island of Hawaii, where the summit reaches to 13, feet 4, meters , contracting altitude sickness hypoxia is a high probability. Before ascending to the summit, visitors must stop at the Information Center, located at an altitude of 9, feet 2, m where they are told to acclimatize to the altitude before proceeding further up the mountain.
In fact, 21 percent of Earth's atmosphere consists of life-giving oxygen 78 percent is composed of nitrogen and the remaining 1 percent a number of other gases.
And the proportion of that 21 percent is virtually the same at sea level as well as at high-mountain altitudes. The big difference is not the amount of oxygen present, but rather density and pressure.
Now picture this: A tall plastic bucket is filled to the brim with water. Now, take an ice pick and poke a hole near the top of the bucket. The water will slowly dribble out. Now take the pick and punch another hole down near the bottom of the bucket. What happens? Down there the water will rapidly squirt out in a sharp stream.
The reason is the difference in pressure. Similarly, the pressure of all the air above our heads is the force that pushes air into our lungs and squeezes oxygen out of it and into our bloodstream.
As soon as that pressure diminishes such as when we ascend a high mountain less air is pushed into the lungs, hence less oxygen reaches our bloodstream and hypoxiation results; again, not due to a lessening of the amount of available oxygen, but to the lessening of atmospheric pressure. So how does atmospheric pressure relate to daily weather patterns?
What is that all about? Basically, in a nutshell, every day the heat of the sun varies all over the Earth.
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