The Water Cycle

The water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. It involves the processes of evaporation, condensation, precipitation, and runoff. Understanding the water cycle is important because it helps us to appreciate the interconnectedness of Earth's systems and how water is constantly being recycled.

Key Processes in the Water Cycle

• Evaporation: This is the process by which water from oceans, lakes, and rivers is heated by the sun and changes from liquid to vapor, rising into the atmosphere.
• Condensation: As the water vapor rises, it cools and condenses to form clouds in the atmosphere. This is a crucial step in the water cycle.
• Precipitation: When the condensed water droplets in the clouds become heavy enough, they fall to the Earth as precipitation, which can take the form of rain, snow, sleet, or hail.
• Runoff: After precipitation, water may flow over the surface of the land and collect in rivers, lakes, and oceans, where the cycle begins again.

Study Guide

1. What are the main processes involved in the water cycle?

Answer: The main processes are evaporation, condensation, precipitation, and runoff.

2. How does evaporation contribute to the water cycle?

Answer: Evaporation is the process by which water changes from liquid to vapor and enters the atmosphere.

3. What happens during condensation?

Answer: During condensation, water vapor cools and forms clouds in the atmosphere.

4. Describe the role of precipitation in the water cycle.

Answer: Precipitation occurs when condensed water droplets in the clouds become heavy enough to fall to the Earth as rain, snow, sleet, or hail.

5. What is runoff, and how does it fit into the water cycle?

Answer: Runoff is the flow of water over the land surface and its eventual return to the oceans, lakes, and rivers, completing the water cycle.

Understanding the water cycle helps us to appreciate the importance of water conservation and the ways in which human activities can impact this vital natural process.