Which processes result in moisture being added to unsaturated air?

The addition of moisture to unsaturated air primarily occurs through processes that involve the transition of water from liquid or solid states into vapor. Evaporation is the process where water from surfaces such as lakes, rivers, or moist soil transforms into water vapor, thus increasing the moisture content of the air. Sublimation, on the other hand, refers to the process where ice or snow directly changes into water vapor without becoming liquid first, also contributing to the humidity of the air.

These processes directly add water vapor into the atmosphere, effectively increasing the moisture level in unsaturated air, which can have implications for weather patterns, cloud formation, and humidity levels. Other processes like condensation and precipitation primarily deal with the removal of moisture from the air rather than adding to it, while cooling and compressing generally relate to changes in air pressure and temperature rather than moisture content. Heating and filtering also do not produce moisture; instead, they modify air characteristics in different ways.