How is moisture primarily added to the air?

Moisture is primarily added to the air through evaporation and sublimation. Evaporation occurs when water from lakes, rivers, oceans, and even soil turns into water vapor due to heat from the sun, effectively increasing the moisture content in the atmosphere. Sublimation, on the other hand, is the process where solid water such as ice or snow converts directly into water vapor without first becoming liquid. Both processes lead to an increase in humidity, contributing significantly to the moisture in the air.

While other options mentioned involve processes that can influence the moisture levels or the climate, they do not primarily describe how moisture is added to the air. For instance, condensation and precipitation involve the transformation of water vapor back into liquid form or solid state, while combustion and photosynthesis involve chemical processes that do not directly contribute moisture but instead alter atmospheric composition. Transpiration and respiration do contribute water vapor indirectly, but they are primarily biological processes and not the main ways moisture is added to the atmosphere on a larger scale. Thus, evaporation and sublimation are the most accurate processes for the primary addition of moisture to the air.