The hydrologic cycle begins with the evaporation of water from the surface of the sea. As humid air is lifted, it cools and water vapor condenses to form clouds. Moisture is relocated around the globe until it returns to the surface as precipitation.The sun's temperature provides energy to evaporate water from the earth's surface (oceans, lakes, etc.). Plants also lose water to the air - this is called transpiration. The water vapour eventually condenses, forming tiny droplets in clouds.