What is the process of cold air and warm air blowing across isotherms called?

The process of cold air and warm air blowing across isotherms is referred to as advection. Advection involves the horizontal movement of air masses, which can carry temperature and moisture characteristics from one location to another. This movement across isotherms, which are lines on a map connecting points of equal temperature, results in the mixing of different air temperatures and can significantly impact local weather conditions.

In contrast, convection refers to the vertical movement of air due to temperature differences—warm air rises while cooler air descends. Diffusion is the process of spreading substances from areas of high concentration to areas of low concentration, generally not directly related to air movement concerning temperature. Condensation is a phase change process where vapor turns into liquid, mainly relevant to moisture in the atmosphere and the formation of clouds, rather than air movement.