Answer: b. it compresses and warms
Explanation:
As an air parcel sinks in the atmosphere, it experiences increasing pressure due to the weight of the air above it.
According to the ideal gas law, when the pressure on a gas increases while its volume decreases, its temperature also increases.
As the air parcel is compressed by the increasing pressure, its volume decreases and its temperature rises. So, the air parcel compresses and warms.
As an air parcel sinks, B) it compresses and warms it expands and warms.
This occurs because, as the parcel descends through the troposphere, it experiences increasing atmospheric pressure. This pressure compresses the air parcel, decreasing its volume. As the volume shrinks, the air molecules collide more frequently, which increases their kinetic energy and thus the temperature of the parcel. This process is known as adiabatic warming.
For example, if you've ever noticed the air becoming warmer as you go down a mountain, that's because the descending air parcels are compressing and warming up due to increased atmospheric pressure.