Which atmospheric condition will decrease air density?

The correct answer is based on the fundamental understanding of how atmospheric conditions affect air density. Air density is influenced by pressure, temperature, and the amount of moisture in the air.

Increasing altitude typically leads to a decrease in air pressure and temperature, which in most cases lowers air density as well. However, the primary factors to focus on are pressure and temperature.

Increasing temperature decreases air density because warmer air has molecules that are moving faster and are spread out more compared to cooler air, which results in lower density.

On the other hand, a reduction in pressure also leads to a decrease in air density since lower pressure allows air molecules to spread out more, thus decreasing the overall density.

When considering decreasing pressure, temperature, and moisture together, all three factors contribute to a decrease in air density, making this option the most comprehensive and accurate in describing how these conditions collectively reduce air density in the atmosphere.