Read the passage: The water cycle describes the continuous movement of water through Earth's systems. Driven by solar energy, water evaporates from oceans, lakes, and soil, rising as vapour into the atmosphere. As this vapour cools at higher altitudes, it condenses into tiny droplets that form clouds. When the droplets grow heavy enough, they fall as precipitation in the form of rain, snow, or hail. Some of this water flows over the surface into rivers and back to the sea, while a portion seeps into the ground, replenishing underground reserves known as aquifers. Vegetation also returns water to the air through transpiration. Because the total amount of water on Earth remains essentially constant, the cycle continually redistributes a finite resource rather than creating new water. According to the passage, clouds form when