Atmospheric science – How does air pressure vary with increasing altitude above the Earth's surface?

Introduction:
Understanding how atmospheric pressure varies with height is fundamental in meteorology, aviation, and fluid statics. Pressure is the weight of the air column above a given point; as you move higher, less air remains above you, so the pressure changes in a predictable way.

Given Data / Assumptions:

• Standard atmosphere assumptions (well-mixed troposphere, no severe weather anomalies).
• Altitude measured upward from mean sea level.
• Temperature lapse rate treated as typical; qualitative trend sought.

Concept / Approach:

The hydrostatic relation dp/dz = − rho * g shows that pressure decreases with increasing altitude z because density rho and gravity g are positive. While the decrease is approximately exponential (barometric formula) rather than linear, the monotonic trend is unambiguous: higher altitude means lower pressure. This behavior affects boiling point, aircraft performance, and human physiology at high elevations.

Step-by-Step Solution:

Verification / Alternative check:

At sea level P ≈ 101.3 kPa; at ~5.5 km, it is roughly half that value under standard conditions. Barometric pressure sensors and altimeters use this principle to infer altitude from pressure readings.

Why Other Options Are Wrong:

Does not change / increases: Contradicts hydrostatic balance and observation.Oscillatory or non-monotonic trends: Do not represent the standard atmospheric profile; local inversions affect temperature, not the monotonic pressure decrease.

Common Pitfalls:

Assuming a linear decrease; the actual dependence follows the barometric formula and depends on temperature profile. For most qualitative engineering problems, “decreases with height” is sufficient.

Final Answer:

decreases