Environmental Enlightenment #310
At the ocean’s surface, evaporation (powered by the energy of solar radiation) converts liquid water into water vapor. This vapor, which contains small amounts of dissolved material, is carried by air masses moving across the ocean.
Approximately 3.6 million tons of water are evaporated annually from an average square mile of the ocean surface.
Moisture-laden air masses rise as they are heated by the sun’s radiation. At higher elevations they expand and cool due to the lower pressure in the upper atmosphere.
The particulate matter provides surfaces upon which water vapor is converted to liquid water or ice. These particles are referred to as condensation or freezing nuclei.
The water droplets or ice crystals then form clouds; and when individual droplets gain sufficient mass, they accelerate downward by the force of gravity and fall as precipitation.