Plants release water vapor through a process called transpiration. This occurs primarily through tiny openings on the undersides of leaves known as stomata. During transpiration, water absorbed by the roots moves through the plant and evaporates into the atmosphere, especially on warm, sunny days. This process helps in cooling the plant and maintains nutrient flow from the roots to the leaves, aiding photosynthesis. Transpiration also plays a significant role in the water cycle, as water vapor released contributes to atmospheric moisture, potentially leading to precipitation.