# Does climate change affect air density at altitude (scale height)?

• Mike S.
In summary, global temperature change affects the tree line and presumably comfortable habitability via temperature, and average air pressure associated with weather patterns. Increases in the volume of the oceans should also push up the atmosphere from below. However, the density of air molecules starts off less because it's hotter at sea level. Then there's the wild card of how much of each gas dissolves into the oceans at different temperatures and pH levels.
Mike S.
TL;DR Summary
Assume a "worst" case scenario of 6 C global warming. Will the air pressure at high altitudes increase significantly due to a change in scale height of the atmosphere and other factors?
Increases in global temperature change affect the tree line and presumably comfortable habitability via temperature, and average air pressure associated with weather patterns. That's not what I mean. I'm thinking a 1/50 increase in kelvin temperature might increase the scale height of Earth's atmosphere by a comparable factor - from, say, 8 km to 8.16 km. Increases in the volume of the oceans should also push up the atmosphere from below. However, the density of air molecules starts off less because it's hotter at sea level. Then there's the wild card of how much of each gas dissolves into the oceans at different temperatures and pH levels. Has anyone worked through all the angles to determine the net effect on the average of all air density at any given altitude above the geoid?

Thanks! The equations given in that source are simple but the semantics are unfamiliar to me, so I'll break them down as I go along.

The simplified approximation is:

PA = (P0 - PAltSet) * 1000 + HAirport
DA = PA + 120 (T - Ts)

P0 is "standard pressure" in inHg, which I would *assume* is 29.92 inHg
PAltSet is an "altimeter setting" in inHg ( a pressure reading from a fixed station at the ground read over the radio to the plane, or in this case, just measured at the airport we're talking about, but apparently representing the hypothetical pressure at sea level given current weather conditions)
HAirport is the elevation of the airport in feet
T = Temperature in C, at the airport in this case
Ts = "standard temperature" in C, and Ts = T0 - 0.002 * HAirport. I might *imagine* T0 is 0 or 25, wait no, 15 C?

Reverse engineering their example from Denver, where H = 4226 ft and DA = "roughly" 6350 ft when T = 25 C and PAltSet = 30.01 inHg, I get PA = 4136 ft, Ts = 6.548, and the 120(T-Ts) is 2214, so that adds up. To rephrase these in equations where I'm not guessing random temperature and pressure adding feet and inches of mercury...

PA = (29.92 inHg - PAltSet) * (1000 ft/inHg) + HAirport
DA = PA + (120 ft/C)* (T + 0.002 C/ft * HAirport - 15 C)
DA = PA + (120 ft/C) * T + 0.24 * HAirport - 1800 ft

Combined,
DA = (29.92 inHg - PAltSet) * (1000 ft/inHg) + (120 ft/C) * T + 1.24 * HAirport - 1800 ft

With the units in place, it looks like the ft/inHg and ft/C may both be at issue in climate computations, but at least I've gotten this far. :)

## 1. How does climate change affect air density at altitude?

Climate change can affect air density at altitude in several ways. One of the main ways is through changes in temperature. As the Earth's average temperature rises, the air molecules in the atmosphere become more energetic and spread out, resulting in a decrease in air density. Additionally, climate change can also alter wind patterns and atmospheric pressure, which can further impact air density at different altitudes.

## 2. Does air density at altitude change in the same way globally?

No, air density at altitude does not change in the same way globally. Climate change can have varying effects on air density depending on factors such as location, altitude, and local weather patterns. For example, some regions may experience a decrease in air density due to warmer temperatures, while others may see an increase in air density due to changes in wind patterns.

## 3. How does air density at altitude affect aircraft performance?

Air density at altitude plays a crucial role in aircraft performance. As air density decreases with altitude, aircraft engines have less air to work with, resulting in reduced engine power and decreased lift. This can lead to longer takeoff distances, reduced fuel efficiency, and potentially impact the ability of aircraft to reach higher altitudes.

## 4. Can changes in air density at altitude impact weather patterns?

Yes, changes in air density at altitude can impact weather patterns. As air density decreases, it can affect the formation of clouds and precipitation, as well as the movement of air masses. This can lead to changes in regional weather patterns and potentially contribute to extreme weather events.

## 5. Are there any potential consequences of changes in air density at altitude due to climate change?

Yes, there can be potential consequences of changes in air density at altitude due to climate change. As mentioned, it can impact aircraft performance and weather patterns. It can also affect the health and well-being of humans and other living organisms, as changes in air density can alter the distribution of oxygen and other gases in the atmosphere. Additionally, changes in air density can also impact the Earth's climate system, potentially leading to further changes in temperature, wind patterns, and precipitation patterns.

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