Grades 3–5 · Systems
How does water move through the water cycle?
A puddle shrinks as water escapes into the air, helped by energy from warmer surroundings and sunlight. Gravity brings water downward again as precipitation and flowing water. These journeys connect oceans, air, clouds, land and underground stores in the water cycle.
During evaporation, liquid water becomes invisible water vapor, a gas. Energy from warmer surroundings helps water escape from a surface; boiling is unnecessary. A shallow puddle can shrink on a sunny day even though no bubbles boil through it. Plants also release water vapor from their leaves.
When moist air cools enough, some vapor condenses into tiny liquid droplets. Clouds contain these droplets or ice crystals, rather than being visible piles of water vapor. Droplets and ice particles can grow until they fall as precipitation, including rain or snow.
Evaporation leads away from the Ocean store, while Condensation and Rain / snow mark cooling and falling water. The Runoff arrow completes this surface route; other water can take different branches.
Evaporation leads away from the Ocean store, while Condensation and Rain / snow mark cooling and falling water. The Runoff arrow completes this surface route; other water can take different branches.
Rain can flow downhill as runoff or enter soil by infiltration, staying underground or moving toward springs and streams. Puddles, trees and groundwater hold water for different lengths of time. A drop has branching possibilities, rather than one required loop to finish.
The water arrows trace a surface route. Sunlight supplies energy for evaporation; gravity draws water downward. Other routes connect plant and underground stores.
About this explanation
Starting knowledge: Recognize liquid water and follow arrows between places.
Sources
- US Geological Survey — Water Cycle Diagrams
- US Geological Survey — Condensation and the Water Cycle
- U.S. Geological Survey — Water cycle