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Transcript of Science
Distribution of Water
About seventy percent of the Earth's surface is covered in water, about ninety seven percent of that water is found within oceans. Only three percent of the planet's water is fresh water, meaning non salty water. Two percent of the Earth's water is frozen in large sheets of ice that are usually found in places such as Greenland and Antarctica. Very little of that clean water is sitting on the surface in streams or lakes. One of the biggest problems society faces, besides Zayn Malik leaving One Direction, is keeping up with the high demand for clean drinking water.
The Water Cycle
Earth is the only planet we know that contains water in three states, or phases. Those three states are solid (in form of ice, snow, and glaciers), liquid (in form of oceans, lakes, and streams), and gas (in the form of water vapour). All of these forms of water are part of one large process called the water cycle.
Heat added to liquid water causes evaporation. This means the water turns from a liquid into a gas (called water vapour).
Heat added to frozen water (for example, an ice cube) causes melting, which means the ice turns into a liquid.
Heat taken away from water vapor causes condensation. This means the vapor turns into liquid water.
Heat taken away from water causes solidification as the water reaches its freezing point (0°C for fresh water) and turns into ice.
If water vapor turns right into a solid (skipping the liquid state), is called deposition. If ice turns right into water vapor (skipping the liquid state), the process is call sublimation.
Ocean water makes up such a large percentage of Earth's water, making the ocean a good starting point for the following water cycle. As the ocean is heated by the Sun, the surface water molecules evaporate. This water vapor rises into the atmosphere and is moved around the globe by winds. When the air is cooled, condensation begins to occur, and then water droplets form. When enough of these small droplets come together, clouds are created. Depending on conditions such as air temperature, air pressure, and winds, the clouds may release water as rain, snow, or any other form of precipitation. Most of the water that reaches the land flows into streams and rivers return to the ocean. And then the cycle goes on again.
A hydrologist is a person who studies Earth's water systems and helps find solutions to problems of water quality and quantity. Hydrologists often work with communities to find a clean and steady supply of water. This is just as important in British Columbia as it is in developing countries of the world. Hydrologists also use their science or engineering skills to control events such as flooding and soil erosion, and to prevent pollution of water sources. Oceanographers are people who study ocean systems, specifically.
10.1 Key Words
Condensation-the process of changing state from a gas to a liquid
Evaporation-the process of changing state from a liquid to a gas
Freezing Point-the temperature at which a liquid becomes a solid as heat is removed
Hydrologist-a scientist who studies Earth's water systems and helps find solutions to problems related to water quality and quantity
Melting-the process of changing state from a solid to a liquid
Solidification-the process of changing state from a liquid to a solid by the removal of heat
Sublimation-the process of changing state from a solid to a gas without going through the liquid stage
The amount of salt dissolved in water is called salinity. Although even fresh water has tiny amounts of salt, ocean water is more than two hundred times saltier. The average salinity in all the world's oceans is about thirty five per thousand percent.This is similar to mixing 35 grams of salt in 1L of water. The salinity in sea water can be different from the rates of evaporation, if the rate of evaporation is higher the rate of salinity will be higher, but if it is lower it will be lower. When the water in the ocean turns into vapor in the air, it leaves salt behind. Water is very salty near the North and South Poles as well, because when water freezes and changes into ice, it also leaves salt behind.
Composition of Salt Water
The salt comes from the water that has been running off the land for millions of years. When the rain falls on the land, most of it goes into the ground or through rocks and then eventually into streams and rivers, those materials are called dissolved solids.
Two examples of dissolved solids are sodium ions (Na+) and chloride ions (Cl-) and with their great powers combined, they form sodium chloride (NaCl), they mix together by the motion of the ocean.
Density of Salt Water
Density is a measurement of the mass of an object that has a given volume. Density is measured in kilograms per cubic meter (kg/m3). Ocean water has a density of 1027 kg/m3 and fresh water has a density of 1000 kg/m3. Meaning you would float more easily in a freshwater lake.
Freezing Point of Salt Water
Ocean Water contains more salt than fresh water does,meaning it's freezing point is -1.9°C, and fresh water's freezing point is 0°C.
10.4 Water's effect on shaping earth
Big glaciers can scrape and cut out whole valleys. Over 10,000 years ago all of BC was covered in ice that made striations and large valleys that are here today. When these big glaciers scrape rock and mountains they also pick up the broken down materials and carry them along the ground, this is called erosion. After carrying along this broken down sediment the glaciers usually deposit or dump these materials where a river meets an ocean or lake, this area of built up sediment is called a delta.
10.4 key words
Weathering- The process of breaking down rock into smaller fragments.
Physical weathering- The gradual process of breaking down rock physically without changing its composition.
Cave- A large underground hollowed in rock created over time by weathering and erosion.
Delta- An area of built-up sediment deposited by a river where the river empties into an ocean or lake.
Deposition- The process in which eroded sediments and other materials are dropped or left by water or ice, creating built-up landforms such as deltas and eskers.
Erosion- The transport of sediments from one place to another by agents such as water, glaciers, gravity and wind.
Karst- An area with many sinkholes.
Landslide- A sudden, rapid movement of rock material down a slope of a hill or mountain.
Rapids- An area of fast moving,churning water in a steep, rocky river.
Striations- Scratch marks on rock created when glaciers slowly move over the rock.
Biological weathering- Physical or chemical weathering caused by plants or animals.
Chemical weathering- The process through which rock is broken down when its minerals react with chemical agents such as oxygen, carbon dioxide, water and acids.
10.3 Sources Of Fresh Water
Factors That Affect Run-Off
Run-Off is why lakes and most of the ocean is still there with close to the same amount water each day and supports most wild life that live in these areas. The way that Run-Off supports wild life is by refilling or keeping the water level relatively the same height which provides feeding grounds to allot of animals, for example bears, ducks, humans and many other animals. This is one of the biggest and most important part to play in the water system. Key word is Run-Off. There are four different factors that affect Run-Off:
1) Ground material: If the ground is pavement then the water will keep moving into pot hole which means a increase in run-off
2) The amount of time it rained for/ and the amount rained: If the ground has already been rained on then it will be saturated, there for water will not be absorbed by the ground which means an increase in Run-Off.
3) The slope of the land : If the land is steep enough to make the water go very fast then the Run-Off will be increased because the ground can easily absorb the water. If the ground is pavement then the water wont be absorbed and Run-Off will be increased by allot)
4) The amount of construction in the area: If there is allot of construction in the area then Run-Off will be increased because on the side of the road there will be little ditches that help control and prevent flooding. Those little ditches can either lead into a lake , river , stream (which then leads to one of them) and the sewer which in the long run also leads to a bigger body of water.
Earths surface can also be changed with weathering. Different types of weathering such as chemical weathering can break down rock on the earth's surface. Chemical weathering involves chemical reactions with substances such as minerals in rock, water and oxygen. Chemical weathering can also occur underground. This is when carbon from organic materials or the carbon dioxide we release mixes with rain water making the water acidic. When this water drains into the ground, it mixes with the ground water and turns it into acidic water. When it touches rocks that have calcium carbonate, the rocks start to fizz and start dissolving. This could make large caves, holes that could lead to sinkholes and sometimes karst.
Landslides are made when slopes or sides of hills or mountains are soaked up with rain water and it is too heavy to hold up causing the rock, soil and other bits to slide down the mountain, often causing lots of damage and destruction.
1. How are caves formed?
2. How are landslides caused?
3. What is a cirque?
4. What is an out wash?
5. What is karst?
1.True or False? Most fresh water frozen in large sheets of ice.
2.What is the difference between Deposition and Sublimation?
3.True or False? The water cycle starts with condensation?
4.Where does salt in salt water come from?
5.What are two examples of dissolved solids?
6.Would it be more easier to float on ocean water or fresh water?
Natural Events And Human Events
If humans inter fear with Run-Off allot of things can happen that have a positive and negitive impact on run off example a bad thing that would affect Run-Off would be: flooding because of dams breaking or dams taking all the water away from a stream or river, which in that case would cause a eco-system to shut down. That example would mean that, during the water that was building up the river or stream would have had a decease at one point but once they had to let out the water there is a massive increase in Run-Off that would then wash away valuable soil.
When it rains the water will go down a path. This path includes, the rain flowing down the road, into a sewer, which then might lead into a bigger body of water like a river that will then lead into a lake or pond. Another example of a Basin Drainage would be a bathroom sink, the way that a bath room sink mimics a bunch of rivers going to gather would be because all the water that comes from the tap or( or clouds) goes into one big hole or( body old water). Almost all small streams and rivers will potentiality lead into a bigger body of water. if you look at picture (2) you will see a pattern that looks allot like the ways a tree's branches form small branches
Features created by Glaciers
Erratic-A large boulder deposited on the ground by a glacier.
Esker-A winding ridge materials deposited by a glacier.
Moraine-A ridge of rocky material deposited by a glacier, mainly found on the sides and on the begining of glaciers.
Outwash-Material deposited by water from a melting glacier.
Arete-A narrow ridge on high ground between two cirques.
Cirque-A bowl-shaped valley on the head of a glacier.
Fiord-A narrow inlet of ocean between steep cliffs carved by glaciers.
Hanging Valley-A U-shaped valley cut off by a bigger valley created by a large glaciers.
Horn-A Pyramid-shaped peak located between three cirques.
Density-the mass of a given volume
Salinity-a measure of the amount of salts dissolved in a liquid
BC science 8 textbook
BC science 8 workbook
10.2, 3 p.368-372-Aiden.G
10.3, 6 p.376-382-Dodge.W
10.4, 8 p.386-396-Brendan.G
Ground water is what makes its way into little space in the rock called pores. If water is flowing in the river some of that water gets absorbed into the ground and put into little air holes of under ground dry rocks. If the ground has lots of water then it is saturated so no more are for water to go into that rock. If a rock has lots of pores then it is called a porous. many people who live in a city get their water from a storage unit that holds water for them. Cities even have lakes near them just incase they need that extra water supplies. these supplies areas are called Reservoirs. people that live away from a city might use a well because they need water, so the idea of getting water from a well you need to know where to dig. You have to dig to the saturation zone where all the water is from the rivers and lakes.
1) what are some factors that effect Run Off?
2) What zone under ground has the most water?
3) What is the rock called when it has lots of pores?