What conditions lead to a Higher Density Altitude?

Higher density altitude occurs under certain atmospheric conditions that affect the density of air. The correct choice identifies a combination of factors: higher elevations, lower atmospheric pressures, higher temperatures, and higher humidity.

Higher elevations result in lower air pressure, which reduces the density of the air. When the air is less dense, it means there are fewer air molecules in a given volume, leading to higher density altitude. Additionally, higher temperatures contribute to this phenomenon because warm air causes air molecules to spread apart, further reducing air density. Finally, increased humidity adds water vapor to the air. Since water vapor is less dense than the nitrogen and oxygen that make up most of the atmosphere, higher humidity decreases overall air density as well.

In contrast, other options do not encompass the complete set of conditions affecting density altitude. For instance, higher atmospheric pressures and lower temperatures would actually lead to a lower density altitude, as more air molecules are densely packed together under those conditions. Lower elevations typically result in higher air pressure and greater air density, which contributes to a lower density altitude, making that option incorrect. Standard atmospheric conditions signify average pressure, temperature, and humidity levels, not conditions that specifically lead to higher density altitude.