the water cycle in this presentation you will: explore the stages of the water cycle classact srs...
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The Water Cycle
In this presentation you will: explore the stages of the water cycle
ClassAct SRS enabled.
The Water Cycle
Water covers the majority of the surface of the Earth. It is vital for life on Earth for two main reasons.
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Firstly, it makes up around 70% of all living things.
Secondly, it provides an environment for those organisms that live in water.
In this presentation you will explore the movement of water around the Earth. This is known as the water cycle.
The Water Cycle
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I. Our Water is Millions of Years Old
A. At one time or another, all the water molecules on the planet have been in an ocean, a river, a plant, an animal, a cloud, a raindrop or a glacier.
B. Another interesting fact is that the water we drink today is the same water that the dinosaurs drank millions of years ago!
The Water Cycle
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II. Water Can Gain Energy
A. Wherever water is on the surface of the Earth, it can be heated by radiation from the Sun. The Sun provides it with energy.
B. The water can be affected by weather conditions too. For example, water in the oceans will form large waves when a storm is near. This also gives large amounts of energy to the water.
Condensation
EvaporationRain
The Water Cycle
1
Which process transfers heat from the Sun to the oceans?
Question
A) Convection
B) Radiation
C) Conduction
D) Correlation
The Water Cycle
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III. Evaporation
B. Evaporation is the changing of a liquid to a gas. During the evaporation process, impurities in the water are left behind. As a result, the water vapor that enters the atmosphere is cleaner.
C. Water can evaporate into the atmosphere from oceans, seas, lakes, pools, snow, and living organisms.
A. The energy that the water gains helps it to evaporate.
The Water Cycle
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IV. Factors that Affect Evaporation
A. The amount of natural evaporation that takes place is affected by the wind. The warmer and drier the wind, the higher the rate of evaporation.
B. The main factor affecting evaporation is temperature. Water evaporates more quickly at higher temperatures.
The Water Cycle
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Which of the following factors does NOT affect the rate of evaporation?
Question
A) Temperature
B) Sea depth
C) Humidity
D) Wind
The Water Cycle
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V. Convection
A. When water evaporates, it becomes water vapor.
C. When a gas is heated it expands, its volume gets larger.
B. The Sun continues to supply energy so the water vapor (a gas) gets warmer.
D. This makes it less dense than the air above it, so it rises.
E. This upwards flow is called a convection current.
The Water Cycle
3
Why does warm water vapor rise?
Question
A) It is less dense than the air above it.
B) It is denser than the air above it.
C) It is denser than the air below it.
D) It is attracted by clouds.
The Water Cycle
VI. Condensation
B. Condensation is the process by which water vapor changes from a vapor to a liquid.
A. As the vapor rises it will also cool down. When it has cooled, it may condense.
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C. Water vapor condenses onto small airborne particles to form dew, fog or clouds.
The Water Cycle
4
Which of the following correctly describes the term 'condensation'?
Question
A) It is the changing of a liquid into a solid.
B) It is the changing of a gas into a liquid.
C) It is the changing of a solid into a gas.
D) It is the changing of a liquid into a gas.
The Water Cycle
VII. Rain, Snow or Hail… its all precipitation
B. If the water drops become large enough, the water will fall from clouds in the form of rain, snow or hail.
A. Clouds contain water vapor and cloud droplets, which are small drops of condensed water. These droplets are much too small to fall out of the cloud, but they are large enough to make the cloud visible.
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C. This delivers the atmospheric water back to the Earth.
D. This process is called precipitation.
The Water Cycle
VIII. Soaking into the Ground
A. Water on the surface soaks into the ground to become groundwater. The rate at which this happens depends upon the permeability of the soil or rock.
B. Groundwater tends to move slowly. In some cases, it can take thousands of years to return as surface water.
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C. Due to the force of gravity, the water returns to the land surface at a lower point than where it entered.
The Water Cycle
IX. Percolation
A. Percolation is the downward movement of water through soil and rock. This occurs below the root zone (the depth of soil penetrated by plant roots).
B. Groundwater percolates through the soil in the same way as water fills a sponge. It moves from space to space along fractures in rock, or through sand or gravel.
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The Water Cycle
5
What name is given to the process of water passing through rocks below the Earth's surface?
Question
A) Evaporation
B) Convection
C) Condensation
D) Percolation
The Water Cycle
X. Run-Off
A. Water that does not soak into the ground or evaporate immediately will run off the land.
B. It will form streams, which in turn form rivers that run into lakes or eventually the oceans.
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C. In this way the cycle will then be ready to repeat itself.
The Water Cycle
Summary
After completing this presentation you should be able to:
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show knowledge and understanding of the stages of the water cycle
The Water Cycle
In this presentation you will: explore the composition of Earth’s atmosphere explore how atmospheric conditions influence the weather explore how natural processes and human activities cause
changes in the atmosphere
ClassAct SRS enabled.
The Water Cycle
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A. The atmosphere is a thin layer of gases that surrounds the Earth. It interacts with the other major systems of the Earth:
1. The lithosphere – the solid part of the Earth
2. The hydrosphere – all water on Earth or in the atmosphere
3. The biosphere – all living organisms
Lithosphere
Atmosphere
Hydrosphere
Biosphere
I. Composition of the Atmosphere
The Water Cycle
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II. Composition of the Atmosphere
A. The atmosphere is made up of a mixture of gases, known as air.
D. In humid conditions, the amount of water vapor in the air is high, causing the air to feel damp, or even sticky. When the levels of humidity are relatively low, the amount of water vapor in the air is low, causing it to feel dry.
B. Air contains many different gases, including nitrogen (the most abundant gas in air), oxygen, argon and carbon dioxide.
C. Small amounts of water vapor are also found in the air. This is known as humidity.
The Water Cycle
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E. The atmosphere contains oxygen that humans and animals need to breathe. Without oxygen, we could not survive on Earth.
G. The proportion of oxygen in the atmosphere is very important. Too little oxygen would make it impossible to breathe. Too much oxygen is also dangerous, as it would react with other elements in the atmosphere, causing fire and destruction. If oxygen increased to just 25% of the atmosphere, much of the vegetation on Earth would be destroyed by fire.
F. The diagram shows the proportions of different gases in the Earth’s atmosphere.
H. The composition of any planet’s atmosphere would have to be very similar to the Earth’s in order to support human life.
Nitrogen78%
Oxygen21%
All other gases1%
The Water Cycle
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A. Although we cannot see or feel air, it has weight, which exerts pressure on the Earth’s surface.
C. People who travel to high altitudes may experience altitude sickness caused by decreasing levels of oxygen. Symptoms include headaches, nausea, dizziness and weakness.
III. Air Pressure
B. Air becomes thinner as it gets further away from the Earth. Because of this, the pressure exerted by the air decreases as altitude (height above a certain point, often sea level) increases.
D. Although altitude sickness is usually temporary, it can become fatal in extreme cases.
Altitudeincreases
Pressuredecreases
The Water Cycle
IV. Layers of the Atmosphere
A. The atmosphere is divided into four layers which extend more than 640 km above the Earth’s surface:
1. Troposphere - from the surface up to between 7 km and 17 km
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2. Stratosphere - from between 7 km and 17 km to about 50 km
3. Mesosphere - from 50 km to between 80 km and 85 km
4. Thermosphere - from between 80 km and 85 km to more than 640 km
Troposphere
Stratosphere
Mesosphere
Thermosphere
The Water Cycle
A. Although the troposphere is the thinnest layer of the atmosphere, it contains a large proportion of the air that makes up the atmosphere.
V. The Troposphere
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B. Most weather occurs in the troposphere. Clouds, which can tell us about conditions in the atmosphere, also form in this layer.
C. Within the troposphere, as altitude increases, temperature decreases. This is why the peak of a mountain may be covered with snow even though the air feels warm at its base.
Altitudeincreases
Temperaturedecreases
The Water Cycle
C. In the stratosphere, unlike the troposphere, temperature increases with altitude.
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VI. The Stratosphere
A. A relatively high concentration of ozone, a form of oxygen, is found in the stratosphere. The ozone absorbs much of the ultraviolet (UV) radiation that reaches the Earth’s atmosphere from the Sun.
B. Without the ozone layer in the stratosphere, much higher amounts of UV radiation would reach the Earth’s surface. UV radiation is potentially harmful to living organisms. It can cause skin cancer and eye damage in humans.
UV radiation
The Water Cycle
A. In the mesosphere, temperature decreases with altitude, as it does in the troposphere. The mesosphere is the coldest layer of the atmosphere, with temperatures dropping as low as -100°C.
VII. The Mesosphere
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B. As you have already seen, ozone absorbs UV radiation from the Sun. The mesosphere is so cold because there is very little ozone to absorb the Sun’s heat in this layer.
C. Most of the meteors that enter the Earth’s atmosphere burn up completely in the mesosphere.
The Water Cycle
VIII. The Thermosphere
B. Radiation from the Sun can cause temperatures in the thermosphere to reach more than 1500°C.
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C. Beyond the thermosphere is a layer of gases known as the exosphere. Only the lightest gases are found in the exosphere. It is only at this point that gases from the atmosphere can escape into space.
A. The thermosphere is the outer layer of the Earth’s atmosphere. This means that it is the first layer to be exposed to the Sun’s radiation.
The Water Cycle
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Most weather occurs in which layer of the atmosphere?
Question
A) The troposphere
B) The stratosphere
C) The mesosphere
D) The thermosphere
The Water Cycle
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I. WeatherA. The properties of the troposphere, such as temperature, water content and air pressure, largely determine the weather.
B. Scientists are able to predict the weather by observing and measuring these properties.
C. Weather often occurs as a result of differences in temperature from one place to another.
The Water Cycle
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Which of the following properties of the troposphere largely determine the weather?
Question
A) Temperature
B) Water content
C) Air pressure
D) All of the above
The Water Cycle
II. Wind
C. When there is a difference in pressure between two air masses, air will move from the area of higher pressure to the area of lower pressure, creating wind. This movement continues until the pressures in the two areas become equal.
A. As the Earth’s surface is heated by the Sun, the temperature of the air immediately above the surface rises. This causes the air to expand, and the air pressure to decrease.
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B. Some parts of the Earth’s surface receive more heat from the Sun than others, causing temperature and pressure differences in the air.
D. Wind can vary in intensity and strength from a gentle breeze to a powerful and destructive storm, such as a hurricane or tornado.
Sunlight
Lowpressure
Highpressure
Wind
The Water Cycle
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"Wind can occur when air moves from an area of high pressure to an area of lower pressure." Is this statement true or false?
Answer True or False.
Question
The Water Cycle
III. Local Weather
A. Local weather is influenced by atmospheric and surface conditions in the local area.
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1. For example, tall mountains can ‘block’ rain by forcing clouds higher into the atmosphere. This can be seen along the Rocky Mountains in the western United States.
B. Winds blow across the US from the west, bringing rainy weather to northern states west of the Rockies. When clouds reach the Rockies, they are forced up, causing rain to fall on the western slopes of the mountains, while very little rain falls on the plains to the east.
C. Local weather is also influenced by global atmospheric conditions. Changes that occur in the atmosphere thousands of miles away can affect the weather.
Wind
Rainy Dry
The Water Cycle
A. Natural processes can cause changes in the atmosphere which affect all life on Earth.
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IV. Changes in the Atmosphere
B. Living organisms produce gases as a result of respiration. Animals breathe out carbon dioxide, while plants produce oxygen. These gases are released into the atmosphere, affecting the composition of the air.
C. Living organisms also produce other gases as waste products. For example, a significant amount of methane is released into the atmosphere by cattle. Methane in the atmosphere helps to keep the Earth warm enough to sustain life.
The Water Cycle
A. Natural processes that do not involve living organisms also affect the composition of the atmosphere.
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V. Changes in the Atmosphere
1. For example, forest fires and volcanic eruptions can cause significant changes in the atmosphere.
B. Smoke, soot and gases such as carbon monoxide released by forest fires can be found in the atmosphere thousands of miles away from the fire itself.
C. Volcanic eruptions release gases, such as carbon dioxide and sulfur dioxide, and water vapor into the atmosphere. Eruptions can also cause temperatures in the atmosphere to decrease.
The Water Cycle
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Human ActivitiesMany human activities release gases and particles into the air. Although the full effects of these materials are not yet known, they can be harmful to the environment and people’s health.
The following are examples of pollutants resulting from human activities:
• Power plants burning fossil fuels emit carbon monoxide and other gases
• Chemicals used in agriculture enter the atmosphere through the water cycle
• Car exhausts emit harmful gases
The Water Cycle
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Human ActivitiesAlthough many of the gases produced by human activities occur naturally in the atmosphere, extra quantities of these gases can dramatically change conditions in the atmosphere.
For example, gases like carbon dioxide and methane trap heat from the Sun, keeping the Earth warm. Although this is a good thing, too much of these gases can lead to dangerous rises in temperatures.
Even small temperature changes can lead to unpredictable, potentially dangerous weather.
Rising temperatures can also cause ice at the north and south poles to melt, raising sea levels and leading to flooding of low lying land.
The Water Cycle
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Pollution and HealthPollutants released into the atmosphere by human activities can damage our health.
For example, pollutants released by motor vehicles and factories react with sunlight, forming ozone close to the ground. Although ozone high in the atmosphere helps to block harmful UV radiation, it is dangerous if breathed in.
When ozone and other pollutants are breathed in, it can cause breathing difficulties in healthy people, and it can worsen the symptoms of people with lung conditions such as asthma and bronchitis.
Pollutants, such as smoke and smog, can also irritate our eyes and skin.
The Water Cycle
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"Only human activities cause changes in the atmosphere." Is this statement true or false?
Answer True or False.
Question
The Water Cycle
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Which of the following is an example of a human activity that causes changes in the atmosphere?
Question
A) Plants release oxygen into the atmosphere
B) Cattle release a significant amount of methane into the atmosphere
C) Power plants burning fossil fuels release carbon monoxide into the atmosphere
D) Animals breathe out carbon dioxide
The Water Cycle
Use energy saving appliances
Unplug appliances that are not in use
Travel on foot or by bicycle instead of
by car when possible
Protecting Air Quality
However, the responsibility for protecting air quality does not belong only to governments and big companies. Everyone can help to look after the environment and our health by being energy efficient. The images on the right show some of the ways you can help to protect air quality.
Recycle your trash
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Many governments have introduced air quality standards and targets to encourage industries to reduce their emissions of harmful substances.
The effects of pollution on health and the environment have led many scientists to stress the importance of ‘clean’ air.
The Water Cycle
Summary
After completing this presentation you should be able to:
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show knowledge and understanding of the composition of the Earth’s atmosphere
show knowledge and understanding of how atmospheric conditions influence the weather
show knowledge and understanding of how natural processes and human activities cause changes in the atmosphere
The Water Cycle
In this presentation you will: explore water as a substance essential for sustaining life explore surface and ground water and how they
replenish each other explore how human activities can affect water quality
ClassAct SRS enabled.
The Water Cycle
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I. Water and Life
A. Water is a compound, a substance made of more than one element (in this case, hydrogen and oxygen).
B. It is the only compound on Earth that is often found as a solid (ice), a liquid (water) and a gas (water vapor).
C. Water is vital to life on Earth. Without water, nothing could survive.
The Water Cycle
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"Living organisms cannot survive without water." Is this statement true or false?
Answer True or False.
Question
The Water Cycle
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II. Water and Life
A. Humans depend on water. For this reason, throughout history, humans have settled near water sources.
B. The most successful civilizations have been those with reliable water sources.
C. Humans have been using water to grow crops for hundreds of thousands of years.
D. Many different ways to harness water for human use have been developed, including:
1. wells2. reservoirs3. irrigation systems
The Water Cycle
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F. In some societies, it became clear by the mid-1800s, that contamination of water sources by waste disposal was causing widespread disease.
G. As a result of this, effective water and sewage treatment processes were developed, helping to prevent water-borne disease.
E. In the past, humans frequently disposed of their waste in rivers and streams. Often, these were the same rivers and streams used to collect drinking water.
The Water Cycle
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III. Fresh Water
A. Most of the water sources on land are fresh water. Unlike the salt water that makes up the oceans and some inland seas, fresh water contains very little salt or other impurities.
B. Fresh water is very important to humans and many other animals because we are only able to drink fresh water.
C. Fresh water has a number of properties that distinguish it from salt water. Fresh water is less dense than salt water. This means that objects float more easily in salt water. Also, fresh water does not conduct electricity as well as salt water.
The Water Cycle
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Inland water sources are...
Question
A) always fresh water.
B) always salt water.
C) mainly fresh water although some are salt water.
The Water Cycle
IV. Surface Water
B. Many different organisms live in surface water. These organisms can be very large, like whales, or microscopic, like bacteria.
A. Surface water is water found on the Earth’s surface. For example: rivers, lakes, streams, wetlands and oceans.
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C. Some sources of surface water are rain and melting snow. It collects on the ground or flows into various bodies of water. Most surface water eventually ends up in the oceans.
The Water Cycle
V. Run-off
B. Gravity is a major cause of run-off, as it pulls water downhill.
A. When water collects on land, it may soak into the ground. Water that does not soak into the ground will run off the land, flowing into larger bodies of water.
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C. As water flows over land, it picks up particles of soil or rock, eroding the ground and forming channels.
D. As more and more run-off occurs, these channels become deeper and wider, eventually forming streams and rivers
The Water Cycle
13
What is run-off?
Question
A) Water that soaks into the ground
B) Water that flows over land into a body of water
C) Water that always ends up in the oceans
D) Water that contains living organisms
The Water Cycle
VI. Watershed
A. A watershed is an area of land over which water flows to a particular body of water, such as a lake or a river.
C. Water on one side of the divide flows into a particular body of water, while water on the other side flows into a different body of water.
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B. Watersheds are separated by divides - land that is at a higher elevation, such as a ridge or a mountain range.
The Water Cycle
VII. Groundwater
A. As you have already seen, some of the water that collects on the surface soaks into the ground, becoming groundwater.
B. The amount of water that soaks into the ground depends on the permeability of the rock or soil at the surface.
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C. Due to gravity, sub-surface water slowly moves down through pores in soil, or cracks in rock (a process known as percolation), eventually reappearing at the surface at a lower elevation.
The Water Cycle
D. As groundwater water percolates through soil and rock, it dissolves some of the minerals contained in the materials it passes through.
E. When water contains a large amount of minerals it is known as hard water. In hard water areas, scale can build up on appliances that use water, such as kettles and faucets, because of the high mineral content of the water.
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The Water Cycle
VIII. AquifersA. Some groundwater water remains in soil pores or small cracks, while some collects in large spaces in rock below the surface.
B. Underground spaces that hold a usable amount of water are called aquifers. The water in an aquifer flows downwards very slowly.
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D. As sub-surface water moves through rock and soil, it can create or enlarge aquifers by the process of erosion.
C. When the water in an aquifer reappears at the surface, it can form a stream, river or spring.
Aquifer
Stream
The Water Cycle
IX. The Water Table
A. When a material becomes so full of a liquid that it cannot hold any more, we say that it is saturated.
B. The water table is the surface of groundwater. Below the water table, pores and cracks in rock and soil are completely saturated with water.
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E. However, the level at which the water table occurs can vary greatly, causing wells to run dry if it sinks, or leading to flooding if it rises.
D. When digging a well or making a pump to collect groundwater, it is important to dig just below the water table to reach water.
C. Water below the Earth’s surface, but above the water table, is sometimes called sub-surface water.
Water table
The Water Cycle
X. The Water Table
A. The location of the water table is related to surface water.
1. For example, heavy rain may mean that more water than usual will seep into the ground, causing aquifers to fill. This in turn causes the water table to rise.
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C. When little or no rain falls for a long time, aquifers may dry out, causing the water table to drop. This also occurs when humans pump water out of an aquifer faster than it is replenished by surface water seeping into the ground.
B. Sometimes, the water table will rise to the surface causing fields and gardens to flood, and nearby rivers to burst their banks. If this is permanent, wetlands are created.
The Water Cycle
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What is an aquifer?
Question
A) An underground space that can store enough water to feed a well
B) A channel cut into the ground by run-off
C) The surface of groundwater, below which, the rock or soil is saturated
D) A small body of surface water
The Water Cycle
XI. Water Quality
A. The quality of a water supply refers to the chemicals it contains.
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C. Some changes to water quality do not pollute the water. However, water pollution can be harmful to living organisms and the environment.
B. The quality of water can be affected by natural events and human activities. For example, the picture shows a river turned red by naturally occurring iron in rocks.
D. The following slides describe some of the major sources of water pollution.
The Water Cycle
Water Pollution
Sewage – Sewage treatment has eliminated water-borne diseases throughout the developed world. However, some parts of the world do not have adequate sewage treatment facilities. In these places, people still die from diseases caused by sewage in water.
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Household waste – Careless disposal of household waste means that hazardous chemicals contained in these products can get into the water supply.
The Water Cycle
Water Pollution
Industrial waste – many industrial processes produce hazardous waste that could cause serious problems if allowed to enter the water supply. For this reason, strict laws are needed to govern the disposal of industrial waste.
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Agricultural run-off – Many farmers use chemical fertilizers to improve crop growth. As run-off water flows over agricultural land, some of these chemicals, as well as waste products excreted by livestock, may dissolve in the water and enter the water supply.
The Water Cycle
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Which of the following are sources of water pollution?
Question
A) Sewage
B) Household or industrial waste
C) Agricultural run-off
D) All of the above
The Water Cycle
Effects of Water Pollution
Water pollution can have devastating effects for organisms that live in or depend on water, as well as the environment.
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Polluted water carries harmful bacteria that can cause disease and death in animals that drink the water or eat fish living in the water. Even people and animals who swim in polluted water are at risk of contracting dangerous diseases.
When polluted water enters the soil, plants and other organisms that get their nutrients from soil will also be affected.
The Water Cycle
Summary
After completing this presentation you should be able to:
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show knowledge and understanding that water is vital to living organisms
show knowledge and understanding of surface and groundwater and how they replenish each other
show knowledge and understanding of how human activities can lead to water pollution