What atmospheric phenomenon is indicated by temperature cooling with increased altitude?

The phenomenon where temperature decreases with increasing altitude is known as the lapse rate. This principle is rooted in the behavior of air in the atmosphere—specifically, as air rises, it expands due to lower pressure at higher altitudes. This expansion causes the air to cool. The lapse rate typically refers to the rate at which temperature drops in the troposphere, which is the lowest layer of Earth's atmosphere. Generally, the average lapse rate is about 6.5 degrees Celsius per kilometer.

In contrast, an inversion is a situation where temperature increases with altitude, which leads to stable atmospheric conditions. A pressure gradient refers to the change in atmospheric pressure across a distance, and it influences wind patterns rather than temperature changes with altitude. Humidity increase pertains to the amount of water vapor in the air, which is not directly related to changes in temperature with altitude. Thus, the lapse rate succinctly describes the correct atmospheric phenomenon of cooling temperatures with increasing altitude.