Water Cycle
The Movement of Water
What is it?
• Our water cycle is a closed system, meaning,
water is not lost nor created.
• Water that falls today, fell before, and will fall
again!
• There are many steps in the water cycle.
Some main parts to the water cycle are:
evaporation, condensation, precipitation,
transpiration, surface runoff, infiltration, and
ground water.
Evaporation
• Liquid water turns into water vapor (caused by
heat)--the Sun’s radiant energy heats water
and causes it to become water vapor
• Most of the water vapor comes from the
oceans—water vapor does not contain salt
• Trees lose water also, this is called
transpiration
Condensation
• Condensation is caused when water vapor
(evaporated water) cools and becomes water
droplets
• These water droplets combine with dust and
other small particles to create clouds
Precipitation
• Water falls to the earth as rain, snow, sleet, or
hail
• This occurs when the water becomes to heavy
to remain in the air
What happens after precipitation?
• Some of the water gets used by living things
(plants and animals)
• Some water seeps into the ground
(infiltration) and becomes ground water
• Some water flows on the ground (surface
runoff) into lakes, rivers, streams, etc.
Transpiration
• Transpiration occurs when water leaves
plants—kind of like a plant sweating
• This is a form of evaporation
Water vapor
leaving the tree
and entering the
air
Surface Runoff
• Surface runoff occurs when precipitation falls
on to hard (impervious) surfaces
• Water cannot penetrate these surfaces so it
can flow directly to a water source (i.e. lake)
• This can cause pollution to the waterways
Infiltration
• Infiltration occurs when precipitation gets
absorbed by the land
• This water can become part of the ground
water (underground bodies of water)
• This process cleans the water
Groundwater
• Groundwater is water that has infiltrated
(penetrated) the ground
• It creates bodies of water underground
• This is a source of drinking water for many
people