Are air masses that form over land moist
Warm air masses usually form in tropical or subtropical regions and are called tropical air masses. Moist air masses form over oceans and are referred to as maritime air masses. Dry air masses that form over land surfaces are called continental air masses
http://wxguys.ssec.wisc.edu/2012/10/15/what-is-an-air-mass/
To determine whether air masses that form over land are moist, we need to consider the characteristics of these air masses.
Air masses are large volumes of air with similar temperature and humidity characteristics throughout. They form over specific regions, either over land or water. The moisture content of an air mass depends on the surface over which it forms.
In general, air masses that form over land are typically drier compared to air masses that form over water. This is because land surfaces heat up and cool down more rapidly than water surfaces. When air masses form over land, they are often influenced by the moisture content of the underlying land surface.
If the land surface over which an air mass forms contains a significant amount of moisture (e.g., near large bodies of water, wetlands, or areas with high humidity), the air mass may become more moist. Conversely, if the land surface is dry (e.g., deserts, arid regions), the air mass is likely to be drier.
To assess the moisture content of an air mass formed over land, meteorologists rely on various measurements and observations such as dew point temperature, relative humidity, and the presence of clouds or precipitation. These data help determine the moisture characteristics of the air mass and provide insight into its potential for moisture content.
In summary, air masses formed over land can vary in their moisture content depending on the characteristics of the land surface over which they form.