Final answer:
Fog can form through condensation, when water vapor cools enough to become liquid droplets, or through rising air currents that cool and condense moisture in the atmosphere.
Step-by-step explanation:
Two basic ways that fog may form are through the process of condensation and by the action of rising air currents that cool and condense moisture in the atmosphere. Condensation occurs when water vapor in the air cools enough to form liquid water droplets, which can happen, for example, when warm, moist air collides with colder air, as seen over San Francisco Bay.
Alternatively, rising air currents can carry water vapor into the atmosphere, which then cools and condenses into tiny droplets, forming fog or clouds.
Fog may form in two basic ways: radiation fog and advection fog.
There are two basic ways that fog may form:
Radiation fog: It forms when the ground cools down at night, causing the air near the ground to cool. If the air cools enough, water vapor in the air condenses and forms fog.
Advection fog: It forms when warm moist air moves over a cooler surface and cools down, causing the water vapor in the air to condense and form fog.