What is a primary source of atmospheric water vapor?

The primary source of atmospheric water vapor is evaporation from oceans. This is due to the vast surface area of the oceans compared to other bodies of water; the oceans cover approximately 71% of the Earth's surface. They play a significant role in the hydrological cycle by providing a continual source of moisture to the atmosphere through evaporation.

The process is facilitated by the fact that warm water from the ocean's surface evaporates more readily, leading to a substantial transfer of water vapor into the atmosphere. This moisture then participates in weather patterns and precipitation processes, making ocean evaporation the dominant contributor to the water vapor content in the atmosphere.

While evaporation can occur from other sources, such as lakes and rivers, the total contribution from these sources is much smaller compared to that from oceans. Hence, other options, while relevant to the water cycle, do not match the scale of the contribution from ocean evaporation.