How does an air mass react when passing over a cold surface?

When an air mass passes over a cold surface, it cools down. As the temperature of the air mass decreases, the ability of that air to hold moisture decreases, which can lead to condensation if the air cools to its dew point. However, in terms of the reaction of the air mass as a whole, this cooling typically suppresses convective currents.

Convective currents are movements of air caused by the uneven heating of the earth's surface, and they thrive in warm air. Since the air mass over a cold surface becomes denser and more stable, it reduces the likelihood of upward air movement and the development of thermal convection currents. This stability can prevent cloud formation and limit vertical development, contributing to a decrease in convective activity.

So, when considering the overall impact of a cold surface on an air mass, the suppression of convective currents is a key reaction due to the increase in stability of the cooled air mass.