In atmospheric physics and meteorology, adiabatic temperature changes in rising and sinking air masses are primarily caused by which one of the following processes?

Introduction / Context:

In meteorology, the temperature of air parcels often changes as they move vertically in the atmosphere. These changes can be adiabatic, meaning they occur without heat exchange with the surroundings, or diabatic, involving heating and cooling from external sources. Understanding adiabatic processes is essential for explaining cloud formation, atmospheric stability and lapse rates. This question asks which process is responsible for adiabatic temperature changes in the atmosphere.

Given Data / Assumptions:

• Adiabatic processes involve no net heat exchange (q = 0) with the environment.
• We consider rising and descending air parcels in the troposphere.
• Pressure decreases with height in the atmosphere.
• Air behaves approximately as an ideal gas over the scales considered.

Concept / Approach:

When an air parcel rises, it moves into a region of lower pressure and expands. This expansion requires the parcel to do work on its surroundings, and since no heat is added in an adiabatic process, the internal energy of the parcel decreases, leading to a drop in temperature. Conversely, when air sinks, it encounters higher pressure, is compressed, work is done on the parcel and its temperature increases. Thus, adiabatic temperature changes are directly tied to expansion and compression of the air, not to processes like radiation absorption or latent heat release, which are non adiabatic and involve energy exchange.

Step-by-Step Solution:

Verification / Alternative check:

Adiabatic lapse rates, such as the dry adiabatic lapse rate of about 9.8 °C per kilometre for dry air, are derived assuming no heat exchange but allowing expansion work. Cloud physics and mountain weather patterns rely on this concept. Latent heat release, on the other hand, modifies the lapse rate and leads to moist adiabatic processes which are not strictly adiabatic in the thermodynamic sense because heat is released or absorbed during phase changes.

Why Other Options Are Wrong:

Option A: Deflection and advection describe horizontal movements and changes in wind direction, not the direct thermodynamic cause of adiabatic temperature changes.

Option B: Latent heat of condensation releases heat and is a diabatic process; it does affect temperature but does not fit the strict definition of adiabatic (q = 0).

Option D: Partial absorption of solar radiation by the atmosphere is a radiative heating process, again not adiabatic because external heat is added.

Common Pitfalls:

Students sometimes use the term adiabatic loosely to include processes where latent heat is involved. In strict thermodynamic terms, adiabatic means no heat exchange with the environment, so latent heat effects actually make the process pseudo adiabatic or moist adiabatic. For exam purposes, always associate adiabatic temperature changes in air with expansion and compression due to pressure variations.

Final Answer:

Adiabatic temperature changes in the atmosphere are caused by expansion and compression of the air.