Key Points

✓The water cycle is the continuous movement of water on, above, and below the surface of the Earth.
✓Evaporation is when liquid water turns into water vapor (a gas).
✓Condensation is when water vapor turns back into liquid water or ice.
✓Precipitation is when water falls back to Earth from the clouds as rain, snow, sleet, or hail.
✓Collection is when water gathers in rivers, lakes, oceans, and groundwater.

The water cycle is how water moves all around the Earth! It's a continuous process, meaning it never stops. It's like a big circle of water changing forms and moving from one place to another. The main parts of the water cycle are evaporation, condensation, precipitation, and collection. First, the sun heats up water in lakes, rivers, and oceans, turning it into a gas called water vapor. This is evaporation. Then, the water vapor rises up into the air and cools down, turning back into tiny liquid water droplets or ice crystals. This is condensation, and it's how clouds form. When the clouds get full of water, the water falls back to Earth as rain, snow, sleet, or hail. This is precipitation. Finally, the water collects in rivers, lakes, and oceans, and the cycle starts all over again!

Worked Example

Imagine a puddle of water on the sidewalk after a rainstorm. The sun comes out and the puddle disappears. What part of the water cycle is this?

Step 1: Identify the starting state. We have liquid water in a puddle.
Step 2: Consider what's happening. The sun is heating the water.
Step 3: Relate to the water cycle. When water is heated, it turns into water vapor (a gas).
Step 4: Identify the process. This is evaporation.

Answer: Evaporation

Try It Yourself

1. What is the process called when water vapor turns into liquid water?

2. Explain how precipitation is important for plants and animals.

3. How might deforestation (cutting down forests) affect the water cycle in a region?

Watch Out For These Mistakes

Thinking that the water cycle only happens in one place, not realizing it's a global process.
Confusing evaporation and condensation.
Forgetting that snow and hail are also forms of precipitation.