Atmospheric pressure is the pressure exerted by the mixture of gases that make up the Earth’s atmosphere on its surface. It is measured in hectopascals or millibars and is represented by the symbol ‘hPa.’ Atmospheric pressure changes according to altitude- the higher we go in the atmosphere, the less air pressure is present. This means that, as altitude increases, air pressure decreases. At sea level, atmospheric pressure is most commonly seen as 1,013.25 hPa.
Atmospheric pressure is also intricately linked to altitude. Generally, as altitude increases, air pressure decreases. This is one of the most important elements of altitude physiology as it affects every living organism. For instance, mountain climbers must constantly monitor and adjust for changes in air pressure and oxygen levels as they ascend higher in the atmosphere. Lower air pressure also does not provide the same level of insulation against the cold, which could potentially cause hypothermia in adventurers, even on surfaces where temperatures may usually be mild. Understanding the effects of atmospheric pressure and altitude on air temperature is a key to conserving energy and staying safe when in mountainous terrain.
Key Takeaways
1. Atmospheric pressure decreases as altitude increases – At sea level, the pressure is approximately 1013 mb.
2. Altitude affects aircraft performance including range, speed, rate of climb and altitude ceiling.
3. Atmospheric pressure also impacts how weather systems develop in an area since it influences the air temperature.
4. Pressure can also be used to measure the density of an atmosphere.
5. The rate of decrease of pressure as the altitude increases is known as the lapse rate.
How Does Atmospheric Pressure Vary According to Altitude?
Factors Impacting Atmospheric Pressure
Atmospheric pressure is the pressure of the atmospheric gases – primarily oxygen, nitrogen, carbon dioxide and water vapor – that wraps around the earth. Pressure can be measured with an instrument called a barometer.
Atmospheric pressure is primarily determined by two factors: temperature and the gravitational force exerted by the Earth. As you ascend in altitude, the air surrounding you gets thinner as it is compressed. This decrease in air density results in a decrease in atmospheric pressure.
Altitude-Pressure Relationship
Atmospheric pressure decreases exponentially, meaning that pressure decreases more quickly as you gain altitude. While atmospheric pressure can vary greatly between locations and climates, for the most part, it decreases by approximately one inch of mercury for every thousand feet of elevation gained.
At sea level, atmospheric pressure is around 14.7 psi, which is equivalent to 760 mmHg. As elevation increases, pressures begins to decline and would reach a minimum of around 4.3 psi (215mmHg) at the summit of Mount Everest, the highest mountain peak in the world.
Immediate Effects of High Altitudes
The decrease in atmospheric pressure at elevated altitudes can have an immediate effect on people. As the atmospheric pressure declines, the body has to work harder to extract oxygen from the air. This can result in lower than normal oxygen levels in the body, causing a medical condition known as altitude sickness. Pressure changes can also cause an increased rate of breathing, changes in heart rate, and even fluid accumulation in the lungs.
Tips for High Altitude Medical Risk Management
When visiting areas at high altitude, it is important to be aware of the associated health risks. Here are some quick tips for managing medical risks at high altitudes:
1. Monitor oxygen levels before and throughout your high altitude stay.
2. Drink plenty of fluids and avoid alcohol and caffeine.
3. Take regular breaks and avoid overexertion.
4. Be aware of signs of altitude sickness and take rest days.
5. Stay below 8000 feet if possible.
6. Never ascend rapidly. Acclimatize by ascending gradually.
What is atmospheric pressure?
Atmospheric pressure is the amount of force that is exerted on any given point due to the air around it. It is measured in atmospheres (atm). The pressure decreases as altitude increases due to the lesser concentration of air molecules at higher altitudes.
How does atmospheric pressure change with altitude?
Atmospheric pressure decreases as altitude increases. This occurs due to the decrease in the atmospheric density with altitude, meaning the air molecules become more spread out as altitude increases. Most aircrafts are pressurised to maintain the same atmospheric pressure at any given altitude.
How is atmospheric pressure used in weather forecasting?
Atmospheric pressure is an important factor in weather forecasting as it helps to measure the strength of the storm systems. Low atmospheric pressure indicates an area of rising air motion, associated with cyclonic activity, while high atmospheric pressure indicates sinking air, usually associated with fair weather.
What is the normal atmospheric pressure at sea level?
At sea level, the normal atmospheric pressure is 1013 mbar, equal to 1013 hPa or 101.3 kPa. This is also referred to as ‘1 atmosphere’.
What is the relationship between altitude and air pressure?
As altitude increases, air pressure decreases, due to the thinner layers of air above preventing the atmospheric pressure from pushing downwards. Conversely, when altitude decreases air pressure increases, due to the increased atmospheric pressure from the layers of air below pushing downwards.
What pressure is considered high altitude?
Pressure is considered high altitude when it is lower than 8700 feet, or 610 mbar. This is due to the fact that the atmospheric pressure at this altitude is lower than the pressure at sea level, and the air is therefore less dense.
What is the pressure at high altitude?
At high altitudes, the pressure is significantly lower than that at sea level. For example, at 12,000 feet the atmospheric pressure is 511 mbar, while at 25,000 feet it is only 241 mbar.
How does altitude affect temperature?
Temperature generally decreases as altitude increases due to the lower air pressure at higher altitdues. In the troposphere, the lowest layer of the atmosphere, the air temperature generally decreases by about 6.5°C (11.7°F) for every 1000m (3280ft) increase in elevation.
How is temperature related to atmospheric pressure?
Temperature and atmospheric pressure are intimately related, as the greater the amount of air pressure, the higher the air temperature. This is due to the fact that air pressure affects the rate of air molecules, which in turn affects the rate of heat transfer.
How does altitude affect atmospheric pressure?
Altitude affects atmospheric pressure in that as altitude increases, atmospheric pressure decreases. This is due to the fact that the air molecule concentration decreases with increasing altitude, therefore the pressure from the surrounding air is lower.
Final Thoughts
Atmospheric pressure and altitude are intimately linked, as changes in altitude have a direct effect on air pressure. This relationship is important to understand as it affects the environment around us, from weather forecasting to aircraft operations. Understanding the relationship between atmospheric pressure and altitude and how these variables interact can provide insight into how weather systems are affected by changing pressures.
Atmospheric pressure is constantly changing due to a variety of factors, such as altitude, temperature, wind, and precipitation. It is important to be aware of how the atmospheric pressure affects the environment as these changes can have a major impact on our lives. Taking the time to understand the relationship between pressure and altitude can help us better prepare for any potential weather-related changes that may occur.
