Do Now:
What is the driving power behind the
water cycle?
 Define the following:

◦ Infiltration
◦ Transpiration
The Water Cycle
Essential Questions
 What
is the water cycle?
 What drives the water cycle?
The Water Cycle
The Water Cycle is the cyclical, solardriven process of evaporation, condensation
and precipitation that controls the
distribution of water on Earth.
The Water Cycle
1.
2.
3.
4.
Evaporation & Transpiration
Condensation
Precipitation
Infiltration, Storage & Runoff
The Water Cycle
The transfer of water into the atmosphere
is accomplished in two ways:

Evaporation
= 90%

Transpiration
= 10%
Evaporation

Evaporation – the process where water
is converted from a liquid to a gas or
vapor; it is the primary means by which
water enters the atmosphere from
oceans, rivers and lakes
Transpiration

Transpiration – the process where
ground water is transported through
plants from roots to pores on the
undersides of leaves where it evaporates
The Water Cycle
After entering the atmosphere, water vapor
can be transported large distances by wind;
as it moves, it condenses into visible
clusters of droplets (clouds).
Condensation

Condensation – the transformation of
water from a gas to a liquid
The Water Cycle
After evaporating into the atmosphere and
condensing, water can leave the atmosphere
via precipitation.
Precipitation

Precipitation – the fall of water
droplets condensed from atmospheric
water vapor down to the Earth’s surface
Rain
Snow
Sleet/Ice
Infiltration, Storage & Runoff
Infiltration – water that
seeps underground into
porous rock/earth
 Storage – water can be
stored as a solid (mountain
snow packs, glacial ice) and
as a liquid (water in
lakes/ponds/ocean)
 Runoff – water that flows
along the surface of the
Earth back to the oceans

What’s Coming Up?
Hydroelectric Plants
 Hydropower & Water Turbines
 Impacts on Environment/Society
