|Mother replied, “At night the ground cools off faster than the water does. That means that the ground becomes colder than the water.”
“The air blows across the cold ground and then across the warmer water,” she continued.
Mary and Marcus looked puzzled. “Fog forms as the water evaporates into the cold air,” she explained.
Mother smiled. “Just wait until the sun warms the ground; then the fog will disappear.”