Atmospheric pressure describes the force exerted by the weight of the air above a specific point on Earth. This force changes depending on location, and elevation has a profound effect on the reading. Denver, Colorado, often called the “Mile High City” for its altitude of approximately 5,280 feet (1,609 meters) above sea level, provides a clear example of how elevation alters atmospheric conditions. The pressure experienced in Denver is significantly less than what is recorded at coastal locations.
The Typical Pressure Reading in Denver
The atmospheric pressure in Denver is consistently lower than the standard pressure at sea level due to its high elevation. Standard sea-level pressure is defined as 101.3 kilopascals (kPa), which is equivalent to 760 millimeters of mercury (mmHg) or 29.92 inches of mercury (inHg).
In contrast, Denver’s average atmospheric pressure is approximately 83 kPa, which translates to about 620 to 630 mmHg or 24.5 to 24.9 inHg. This means the air pressure in Denver is roughly 18% less than at sea level.
Weather systems cause daily fluctuations around this average. High-pressure systems will temporarily increase the reading, while low-pressure systems, often associated with storms, will cause the pressure to dip further. Despite these changes, the overall pressure baseline remains dictated by Denver’s elevation.
Why Altitude Determines Atmospheric Pressure
The fundamental reason for Denver’s lower pressure is related to the physics of the atmosphere’s total mass. Atmospheric pressure is simply the weight of the entire column of air directly above a location. At sea level, this column of air extends from the ground all the way to the edge of space.
When a location is elevated, the air column above it is physically shorter. Moving up 5,280 feet removes a significant portion of the atmosphere’s total mass that would otherwise be pushing down. Consequently, there is less air pressing on the surface, which results in a lower barometric pressure reading.
This relationship is an inverse one: as elevation increases, atmospheric pressure decreases. The atmosphere’s density is greatest near the Earth’s surface because the lower layers are compressed by the weight of the air above them. Since Denver sits within the less-compressed upper layers, the air is often described as being “thinner” or less dense than at sea level.
How Low Pressure Affects the Human Body
The lower atmospheric pressure in Denver directly impacts the amount of oxygen available for breathing. Although the air still contains the same percentage of oxygen (about 21%), the total number of gas molecules inhaled with each breath is reduced because the overall pressure is lower. This reduction is scientifically described as a lower partial pressure of oxygen.
The lower partial pressure means less oxygen is available to diffuse into the bloodstream through the lungs, a condition known as hypobaric hypoxia. Most people who visit Denver will experience mild physiological responses as their body attempts to adjust to this change. These responses include an immediate, increased breathing rate to take in more air and a slightly elevated heart rate.
Visitors, particularly those coming from sea level, may experience mild altitude sickness symptoms within the first 6 to 24 hours. These symptoms often include a headache, fatigue, dizziness, or mild nausea, and they typically resolve within a day or two as the body acclimatizes. For daily life, the lower pressure also means that water boils at a slightly lower temperature than 212°F (100°C), which can affect cooking times.