American Meteorological Society Certification (AMS) Practice 2025 – Complete All-in-One Guide to Certification Success

As altitude increases, air density decreases primarily due to the decrease in atmospheric pressure and temperature at higher elevations. The atmosphere is made up of various gases, and as you ascend, the weight of the air above you decreases. This results in fewer air molecules in a given volume, leading to lower air density.

Additionally, the effects of temperature also contribute to this phenomenon; as altitude increases, the temperature often drops in the lower part of the atmosphere (the troposphere), which can cause air to expand and further decrease density. This relationship between altitude and air density is a key concept in meteorology, as it influences weather patterns, aircraft performance, and the behavior of various atmospheric phenomena.

In summary, the correct answer reflects the well-established principle that air density decreases with increasing altitude.