Earth's Water
 |
Where is all the water on the earth? |
The Water Cycle is the
movement of water continuously from one place on earth to another.
The sun's energy drives the water cycle.
 |
There are six important processes
that make up the water cycle.
Evaporation Condensation Precipitation Surface Runoff Infiltration Transpiration |
| Water has three phases:
liquid solid gas water ice water vapor |
Phase changes:
evaporation - liquid
to gas
condensation - gas
to liquid
|
As the water evaporates,
vapors rise and condense into clouds. The clouds move over the land, and
precipitation falls in the form of rain, ice or snow. The water fills streams
and rivers, and eventually flows back into the oceans where evaporation
starts the process anew.
Water's state (solid, liquid or gas) is determined mostly by temperature. Although water continuously changes states from solid to liquid to gas, the amount of water on Earth remains constant. There is as much water now as there was hundreds of millions of years ago.
Get the whole story here:
www.angelfire.com/nj/PflommScience/H20Cycle.htm
www.angelfire.com/nj/PflommScience/surfacetension.htm
http://ga.water.usgs.gov/edu/
The state says you need to know this
about water:
B. THE MOVEMENT OF WATER THROUGH AN
ECOSYSTEM IS CALLED THE HYDROLOGIC CYCLE.
1. Water goes through
the process of evaporation, condensation, precipitation, and runoff.
*
2. Water is a solvent.
As it passes through the hydrologic cycle it dissolves minerals and gases
and carries them to the oceans.
3. Living organisms
remove, use, and return water to the atmosphere.
4. Fresh water,
limited in supply, is essential for life and for most industrial processes.
Rivers, lakes, and groundwater can be depleted or polluted, becoming unavailable
or unsuitable for life.
OCEAN WATER
Properties of ocean water:
Salinity - means the amount
of salt in the ocean water. The average is 34.5g/kg (34.5 grams of salt
per kilogram of water) Ocean water is salty because small amounts of gases,
elements, and salts dissolve in rivers as they flow across the land.
After it reaches the ocean, some of the water evaporates, but the dissolved
substances remain behind. The dissolved salts cause the salinity.
Salinity differs in different parts of the world ocean. - High salinity
in areas of high evaporation, low rainfall, and warm water.
Low salinity in areas where large rivers
flow into the ocean, mixing fresh water or in areas of high rainfall or
melting ice.
Temperature -
warm surface waters
thermocline (a zone of rapidly changing temperatures)
cool, deep waters
Density - ocean water is more dense than fresh water. Higher salinity and cooler temperature will make ocean water denser.
Pressure - nearer the bottom
the pressure is greater than the pressure near the surface
Current – a flow of water moving
through the ocean. Currents flow horizontally, vertically, near
the top, or the bottom of the ocean.
Surface currents – are driven
by winds blowing over the ocean’s surface. The path of the winds
curves because of the Coriolis Effect.
(The bending of the earth’s winds and currents because of the earth’s rotation)
Winds blowing toward the poles curve
eastward.
Winds blowing toward the equator curve
westward.
Gyre - circular pattern of surface
currents. In the Northern Hemisphere, they flow clockwise. In
the Southern Hemisphere , they blow
counterclockwise.
Deep currents – do not generally
mix with surface currents. They flow from the poles toward the
equator. Density differences keep these
currents flowing. The Coriolis effect bends these currents.
(near the poles ice forms and salts
concentrate in the remaining water. This results in very dense cold water
with high salinity that sinks downward and flows toward the equator.)
Upwelling – the upward movement of deep water near the coasts. Fish are plentiful here.
Shoreline currents – near the shore, travel short distances
El Nino – a disturbance of ocean currents
and winds (occurs every 3 to 8 years)
