What happens to temperature in the troposphere as altitude increases?

In the troposphere, which is the lowest layer of Earth's atmosphere, temperature generally decreases with increasing altitude. This trend occurs due to several factors, primarily the fact that the troposphere is heated from the Earth's surface. The ground absorbs sunlight and radiates heat, warming the air directly above it. As you move higher up in this layer, the influence of this surface heating diminishes, leading to lower temperatures at higher elevations.

This decrease in temperature with altitude is characterized by an average lapse rate of about 6.5 degrees Celsius per kilometer. It's important to note that while localized conditions, such as thermal inversions, can cause variations in this pattern (where temperature might increase with altitude in certain circumstances), the overall and most common trend within the troposphere is a decrease in temperature as one ascends.

The other choices do not accurately reflect typical behavior in the troposphere; temperature does not continue to increase, remain constant, or fluctuate in a regular manner as one gains altitude in this layer of the atmosphere.