6th Grade Chapter 16- water cyclePresentation Transcript
Water Chapter 17
The water cycle
All of the water that is part of Earth is called the hydrosphere.
There is a constant cycle of water between the atmosphere and the hydrosphere that plays a big role in determining weather patterns and climates.
Bodies of water evaporate due to the suns energy and enter the atmosphere as water vapor.
When the water vapor cools it returns to earth as liquid in the form of rain or solid snow.
That cooling process of water vapor is called condensation.
The water cycle
When condensation occurs very high with in the atmosphere, clouds form.
Clouds are made of tiny water droplets that eventually collide with other tiny water droplets to form rain.
The rain that falls from clouds is called precipitation. And completes the water cycle.
Some rain water soaks through the ground while some evaporates into gas. The rain water that doesn’t do wither one of these, runs over the ground and ends up in lakes, streams and oceans and is called run off.
The amount of rain and how long it rains for are two factors that affects run off.
Light rain over a long period will have time to soak into the ground, where as heavy rain over a short period of time will not.
Another factor for the amount of run off is steepness or slope of the land, because gravity causes water to move down slopes more rapidly.
When water moves down a slope quickly, it does not have a chance to soak into the ground and vice versa.
Vegetation increases the amount of water soaked into the ground. The presence of plants, slows down water and allows it to be soaked into the ground better.
When water travels down the same slope time after time, it erodes a path into the slope.
As water continues to move down this path, it creates a groove on the slope called a channel.
River System Development
Streams are part of river systems. The water comes from rills, gullies and smaller streams that are upstream.
Run off enters streams, and these streams flow into rivers.
A drainage basin is the area of land from which a stream or river collects run off ( like a bathtub). Like water in a bathtub goes towards the drain, water in a river system flows to the main river. The largest one being the Miss. River drainage basin.
Stages if Stream Development
Streams are classified as young, mature, or old.
Young streams flow swiftly through steep valleys. They may have white water rapids and waterfalls.
Mature streams is the next stage, and it flows more smoothly through its valley. A mature stream erodes along its sides and causes curves to form. Water in a shallow area will move slower, and water in a wider part of the channel will flow faster.
As the curve of a mature stream becomes a broad arc, it is known as a meander
This is the last stage. Ole streams flow smoothly through a broad, flat flood plain, the flat valley floor formed by a meandering stream.
Old streams meet at drainage basins and form a major river.
Water that soaks into the ground and collects in the pores of the soil is called ground water
Scientists estimate that 14% of fresh water on Earth exists as ground water.
Soil and rock are permeable because the pore spaces are connected and water can pass through them. Rock and soil that do not have large connected pores are considered impermeable and water cannot pass through them.
Importance of the ocean
The oceans are important sources of food, energy and minerals for many living organisms.
Energy sources like coal and oil can be found underneath the ocean floor.
1/3 of the worlds table salt is taken from the oceans salt water.
They also make the transportation of goods, by ship, possible.
When the Earth first formed, its surface was mostly volcanoes and cooled volcanic rock.
When all of these volcanoes erupted, they released a lot of water vapor into the atmosphere.
Over millions of years this water vapor gathered in the atmosphere and condensed to form torrential rains which formed our oceans today.
The oceans contain dissolved gasses like oxygen, carbon dioxide, and nitrogen.
Waters salinity is the measure of dissolved salt in seawater. Today's average is 3.5% of the oceans water is salt.
The oceans also contains many dissolved salts along with other elements like calcium, magnesium, and sodium.
Because the demand for freshwater is so high, scientists are trying to come up with technology to take the salt out of water.
They are doing so by using a desalination plant.
This is a large peaked roof building that is filled with saltwater from oceans.
The room is heated so the water evaporates and condenses on the ceiling, once it condenses, it then drips down the ceiling as freshwater into drums.
An ocean current is a mass movement, or flow of ocean water. They are like rivers within oceans.
Surface currents move water horizontally and are powered by winds. These winds force the currents to move in a circular motion.
These currents only move the upper few hundred meters of ocean water.
Warm currents are shown with red lines and cold ones with blue lines.
West coast currents of the U.S. originate at the poles and move down past Cal.
Surface currents that flow along the East coast of the U.S. originate near the equator and are warmer.
Tides are the rise and fall of sea level. They are created by giant waves that are produced by the gravitational pull of the sun and moon.
Water levels moves out at low tide and rise again at high tide. Tidal range is the difference between high and low tide ocean levels.
Oceans react to the pull b/w the earth and moon. 2 budges of water are always forming when the moon rotates the earth
Tides and the moon
Oceans react to the pull b/w the earth and moon. 2 bulges of water are always forming when the moon rotates the earth.
One is going to be where the moon is closest to the earth and the other on the opposite side.
These bulges cause high tides where the moon is closest to the earth, and the areas of the earth that the moon is not over at that time experience low tides.
Spring and Neap tides
When the sun, moon and earth are all lined up it causes more gravitational pull and creates spring tides, which make high tides higher and low tides lower than normal.
When the sun, earth, and moon are at right angles to each other they cause neap tides, which give lower high tides and higher low tides than normal.