- Condensation forms when water changes from a vapor to a liquid. In the process, molecules become more organized, as opposed to the random structure of water vapor molecules. This all occurs as the water is cooled and there is less heat energy for the individual molecules and particles to move around. It then condenses.
- Water is always present in the air, even if it cannot be seen, which makes clouds the most common example of water condensation. Individual water molecules combine with particles of dust, salt and smoke to form cloud droplets, which combine to create clouds. When water droplets become too heavy to be supported by the air below, precipitation occurs.
- Fog is also a result of condensation. Basically a cloud near the ground, fog forms when air with high humidity moves near a colder surface. The air then cools to the dew point temperature and, with additional cooling, water vapor condenses and low-level clouds form.
-
Condensation also forms as a result of man-made processes. For instance, airplanes flying at high altitudes cause trails of condensation to form behind them, called contrails. Because airplanes travel in very cold high altitudes and their exhaust contains water vapor, it condenses into a trail as the plane moves, becoming a cirrus cloud.
There are estimates of cloud cover increasing by as much as 20 percent, and some scientists think contrails play a role in that phenomenon because cirrus clouds reflect sunlight and prevent heat from leaving the surface.
