Post on 11-Jan-2016
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Natural CyclesC22 – C35
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Natural Cycles of the Earth
There are 3 important cycles to study in this unit:
1-THE WATER CYCLE
2-THE CARBON CYCLE
3-THE NITROGEN CYCLE
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The Water CycleO Most of Earth’s water is in the ocean.O The water cycle is the movement of water
through Earth’s ecosystems. Water travels to all the parts of the environment.
1- Evaporation2- Condensation3- Precipitation4- Transpiration5- Ground Water6- Runoff
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EvaporationO The water cycle depends on energy
from the sun to move water around the Earth.
O This causes water in lakes, ponds, rivers, and oceans to change from liquid water to water vapor.
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CondensationO Water vapor changes from a gas to a
liquid in condensation. When water vapor condenses on dust particles in the air, clouds form.
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PrecipitationO Precipitation returns the water to
Earth’s surface. O Water vapor does not contain any
minerals, so precipitation is fresh water.
O RainO SleetO SnowO Hail
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TranspirationO Plants lose water to the air in a
process called transpiration.O This is similar to ‘sweating’ in
humans.
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Ground WaterO Some precipitation soaks into the
ground. O Some water flows underground
until it reaches the ocean or another body of water.
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RunoffO Some precipitation flows along the
surface of the land. In time, it reaches the ocean, lakes, rivers, and streams.
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The Carbon CycleO Living things are largely made up of
carbon.O Plants use carbon dioxide when they
make food in photosynthesis.O The carbon cycle is necessary for
plant growth.O The flow of carbon as a solid, liquid
and a gas through Earth’s ecosystems is the carbon cycle.
O See pp. C24 – C25.
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The Nitrogen CycleO The Nitrogen Cycle moves nitrogen
through the ecosystem.O Cells are made of protein, protein is
made of nitrogen.O Nitrogen goes up into the air
through decomposition of plants and animals.
O See p. C26.
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Reusable ResourcesO Reusable resources can be used
again and again.O Examples are water, carbon dioxide,
oxygen and nitrogen.O Aluminum is reusable if it is
recycled.
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Renewable ResourcesO Renewable resources can be
replaced within a human life span.
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Nonrenewable Resources
O Resources that cannot be replaced within a human life span. Once used, they are gone forever.
O Coal, oil, gas, electricity, and minerals.
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Humans Can Alter Ecosystems
O One of the factors affection Earth’s ecosystems is human activity.
O Burning fossil fuels causes pollution, which is cycled through the ecosystem.
O Acid Rain damages stone and metal structures, crops, leaves, stems, plants and is soaked into roots.