Water
How much of the Earth’s surface is
covered by water?
Three-fourths of
the Earth’s
surface is
covered by
water.
Drinkable water
How much of Earth’s water is
drinkable?
Most of the water
on Earth, 97% to
be exact, is salt
water found in the
oceans. Only
about 3% is fresh
for drinking and
irrigation.
Water
How old is the water you drank at
this morning?
The water in your glass
may have fallen from the
sky as rain just last
week, but the water
itself has been around
pretty much as long as
the earth has!
Water Properties
A water molecule consists of one atom of
oxygen bound to two atoms of hydrogen.
States of Matter (phases)
Water can be found as a solid, liquid or gas.
Water's state is determined mostly by temperature.
Molecules
Small pieces of water are called molecules.
Molecules are always moving.
Solid, liquid, gas
Solid: The molecules
are relatively close to
one another, and the
motion of each
molecule is restricted
by its interaction with
other molecules.
Liquid: The molecules
are further apart and
are not arranged in
any special order.
They are free to move
in any direction, but
are confined by their
container.
Gas: The molecules
are further apart and
have little interaction
with one another.
Density at Freezing
39°
32°
Freezing/Melting
• Freezing turns a
liquid into a solid.
• Melting turns a
solid into a liquid.
Condensation and Evaporation
• Condensation is a
gas changing into a
liquid.
• Liquids evaporate
into gases.
Sublimation and Frost
• Sublimation is a
solid changing
into a gas.
• A gas becomes
solid through
deposition.
Water Cycle (Hydrologic Cycle)
Water is constantly being cycled
between the atmosphere, the ocean
and land. This cycling is a very
important process that helps sustain
life on Earth.
Condensation
Precipitation
Each part of
the cycle
drives the
other parts.
Evaporation
Infiltration
Evaporation
Evaporation is the process where a liquid
changes from its liquid state to a gaseous
state.
Approximately 80% of all evaporation is from the oceans, with the
remaining 20% coming from inland water and vegetation.
Only about 10 percent of the water evaporated from the oceans is
transported over land and falls as precipitation. Once evaporated, a water
molecule spends about 10 days in the air.
Humidity
Most of the time, you can't see it, but the air
contains a lot of water. The amount of water
in the air is called humidity. The
atmosphere is the super-highway of the
water cycle.
Wind speed: the higher the wind speed, the more evaporation.
Temperature: the higher the temperature, the more evaporation.
Humidity: the lower the humidity, the more evaporation.
Transpiration
Transpiration is the loss of water from the
leaves by evaporation; this helps keeps
water moving round the plant by sucking
water up from the roots.
10% of total evaporation
Condensation
Condensation is the opposite of evaporation.
Condensation occurs when a gas is
changed into a liquid.
Cloud Formation
In the United
States, there are 40
trillion gallons of
water above your
head on an
average day.
Cloud Formation
When the air cools, water vapor
condenses into tiny water droplets,
which form clouds.
Condensation Nuclei
The particles around which water vapor
condenses are called condensation nuclei.
Some condensation nuclei are smoke, dust,
or salt crystals from the ocean.
Three Main Ingredients
• Moisture
• Cooling air
• Condensation Nuclei
What stops a cloud from falling?
1 mile in
diameter and
300 feet thick
Stratus and Cumulus
The word stratus comes
from the Latin word that
means "to spread out."
Stratus clouds are
horizontal, layered
clouds that stretch out
across the sky like a
blanket.
The word cumulus comes from
the Latin word for a heap or a
pile. Cumulus clouds are puffy
in appearance. They look like
large cotton balls.
Cirrus and Nimbus
The word cirrus comes from the
Latin word for a tuft or curl of hair.
Cirrus clouds are very wispy and
feathery looking.
Nimbus means rain cloud.
Cumulus
Stratus
Cirrus
Cumulonimbus
Precipitation
When the temperature and atmospheric
pressure are right, the small droplets of
water in clouds form larger droplets and
precipitation occurs.
Cloud Droplet – Rain Drop
Collisions and Coalescence
Precipitation
Rain or Snow?
Hail
Runoff and Infiltration
• Once the precipitation hits the ground:
– It may become run-off
– It may be soaked into the ground (infiltration)
Infiltration
Infiltration is an important process where
rain water soaks into the ground. Water
that infiltrates the ground becomes
groundwater
making up an
aquifer.
Infiltration
As the water infiltrates through the soil and
rock layers, many of the impurities in the
water are filtered out. This filtering process
helps clean the water.
Infiltration
Slope
Vegetation
2
1
3
4
5
Aquifer
Aquifer is the term given to a rock unit that
will yield water in usable quantities to wells
or springs. Aquifers must be both
– Porous
– Permeable
Snake River Aquifer
How Fast Does It Move?
Twin Falls
Idaho Falls
Craters of the Moon
Less than 50
50-100
100-200
200-300
More than 300
Surface Runoff
If precipitation occurs faster than it can
get into the ground, it becomes runoff.
Runoff remains on the surface and flows
into streams,
rivers, and
eventually lakes
or the ocean.
Surface Water
Any water that travels or is stored on top of
the ground.
If you were a drop of water….
Reservoir
Approximate Residence
Time
Glaciers
40 years
Seasonal Snow Cover
0.4 years
Soil Moisture
0.2 years
Groundwater: Shallow
200 years
Groundwater: Deep
10,000 years
Lakes
100 years
Rivers
0.04 years
Most Important Element
Words to Remember
•
•
•
•
•
•
•
Evaporation
Transpiration
Condensation
Precipitation
Surface Runoff
Infiltration
Aquifer
If you were a drop of water:
• In a river (surface
runoff)
– To a lake
•
•
•
•
•
Groundwater
Animal
River
Clouds
Stay in lake
– To groundwater
(infiltration)
• Lake
• Stays in groundwater
• River
– To the ocean
• Clouds
• Stay in ocean
– To an animal
• Soil
• Clouds
• Stay in animal
– To clouds
(evaporation)
•
•
•
•
•
Soil
Glacier
Lake
Ocean
Stay
• In a one hundred year period, an average water
molecule spends 98 years in the ocean, 20
months as ice, about two weeks in lakes and
rivers, and less than a week in the atmosphere.
• One inch of rain falling on one acre of land is
equal to about 27,154 gallons of water. (United
States Geological Survey)