Which term refers to moisture that appears when water vapor condenses on surfaces near the ground, typically overnight or in the morning?

• A. Fog
• B. Frost
• C. Dew
• D. Clouds

Answer: (A)

Moisture seen on surfaces near the ground in the overnight or morning is dew. It forms when the air near the ground cools enough for water vapor to condense directly onto surfaces such as grass, leaves, or a car roof. That cooling happens most on clear, calm nights when heat radiates away from the surface, driving the temperature down to the dew point. If temperatures drop below freezing, the moisture instead becomes frost. Fog, by contrast, is a fog bank of tiny droplets suspended in the air near the ground, which reduces visibility rather than depositing on surfaces. Clouds are condensed water vapor at higher altitudes, not on surfaces at ground level.