Transcript The Water Cycle 9/4/15

Do Now for Friday, Sept. 4th
• In no less than one sentence, describe the
main source of the water cycle!
Water – Water!
Fresh Water
The Water Cycle
• Water on Earth:
– Oceans
– Ice
– Rivers and Lakes
– Below Earth’s Surface
Of all the water on our planet, how much is fresh
water?
Where is most of this fresh water located?
97% Salt Water
3% Fresh Water, mostly in the form of ice
Less than 1% of Earth’s water is available to humans
The Water cycle
Water vapor in the atmosphere!
The movement of water throughout Earth, from
the oceans, to the sky and above and below the
surface is called the Hydrologic Cycle.
The Water Cycle = The Hydrologic Cycle
Evaporation – When water molecules
absorb enough energy to change from
a liquid to a gas.
Heating water causes it to evaporate
more rapidly!
Condensation is the process by which a gas, such as
water vapor, becomes a liquid.
What Happens to the energy in water molecules as
they condense?
Before condensation can occur, the air must be
saturated.
Condensation occurs when saturated air cools.
Condensation on your glasses!
Air can become saturated when water vapor is added
to the air through evaporation.
Air can also become saturated when it cools
to its dew point.
The dew point is the temperature
at which a gas condenses into
a liquid.
At its dew point, air is saturated.
The temperature of the air at a particular location at
which saturation occurs and water vapor
begins to condense forming Dew.
Dew is commonly observed on the leaves
of plants in the early morning.
Sublimation is that process by which
ice turns directly to a gas.
Precipitation
When water from the air returns to Earth’s surface, it is
returned as precipitation.
5 major forms of precipitation:
* rain
* sleet
* freezing rain
* snow
* hail
RAIN
•the most common form of precipitation
•clouds produce when the water
drops become large enough to
fall
•a water drop in a cloud begins
as a droplet smaller than a
period at the end of a sentence –
it must increase its size 100 times
before it will be large enough to fall
Freezing Rain
*Raindrops falling through cold air freeze when they
touch a cold surface (like roads & sidewalks).
*This thick layer of ice can break branches and snap
power lines.
Sleet forms when
rain falls through a
layer of freezing air,
which produces
falling ice.
Snow forms when
temperatures are so
cold that water
vapor changes
directly into a solid.
Snow can fall as
single ice crystals or
can join to form
snowflakes.
SLEET AND SNOW
HAIL
•balls or lumps of ice that
fall from clouds
•form in cumulonimbus
clouds
•when updrafts of air in
clouds carry raindrops
high in the clouds, the
raindrops freeze
•As hails falls, water drops
coat it, another updraft
sends the hail up again
(over and over) until it
becomes too heavy
How to Measure Rain!
• We use a rain gauge to measure rain.
• Most give the calculated rainfall amounts.
Some require calculations.
Snow Calculations
• For snow: 10 in. of snow = 1 inch of rain
•
10 cm. of snow = 1 cm of rain
Runoff water stays on top of the
ground to form rivers, lakes and
streams.
Controlling Precipitation
• A DROUGHT is a long period with very
little or no rain.
• Effects of drought range from loss of crops
to loss of life. Causes famine in many
areas.
We use the term “AQUIFER” to
describe water that infiltrates,
permeates, passes below the surface
and collects underground.
How Do People Use Water?
Agriculture
Industry
Transportation
Recreation
Water and Living Things
• Necessary for growth, reproduction
and other important life processes.
• Name a few “life processes.”
• Respiration
• Movement
• Excretion