What are the processes by which moisture is added to unsaturated air?

• A. Evaporation and sublimation
• B. Evaporation and condensation
• C. Condensation and deposition
• D. Sublimation and deposition

Answer: (A)

Moisture enters unsaturated air when water changes from a liquid or solid into vapor. Evaporation is the process where liquid water from surfaces such as lakes, soil, or vegetation turns into water vapor, increasing the air’s humidity. Sublimation is when solid water (ice or snow) changes directly to water vapor, which also adds moisture to the air.

In contrast, condensation and deposition remove moisture from the air by turning vapor into liquid or solid, so they decrease, rather than increase, the moisture content of unsaturated air. Hence, evaporation and sublimation are the processes that add moisture to unsaturated air.