1. Planet Earth http://youtu.be/vNaXxXNFOjM
Chapter Two

2. The Earth and the Sun’s Energy
All life on Earth requires solar energy, or energy from the sun, to survive
Amount of solar energy received changes constantly
Earth’s rotation, revolution, tilt, and latitude all affect the amount of solar energy Earth receives

4. Rotation
Earth spins on its axis-an imaginary line that runs through the center of the planet around which it turns
It takes 24 hours to make one rotation, or complete spin on its axis
As earth spins, different parts of the planet face the sun, causing the changes from day to night

5. Revolution Earth follows an orbit or path around the sun
Orbit is not a perfect circle
It takes 365 ¼ days to complete one revolution, or trip around the sun
Our calendar is based on the time it takes Earth to complete its orbit
Stop at 1:53

6. Tilt Earths axis is tilted at an angle of 23 ½ degrees from vertical
At any given time on Earth, some places on Earth tilt toward the sun, and others tilt away
Places tilting toward the sun receive more solar energy and have warmer temperatures than those that tilt away

7. Latitude
Latitude is the distance north or south of the Earth’s equator
Low-latitude areas, those nearest to the equator, receive direct rays from the sun all year
High-latitude areas, those farther from the equator, receive indirect rays from the sun and have colder temperatures

8. Seasons Earth’s seasons are caused the planets tilt
Many places experience four seasons
Winter, spring, summer, fall
In some parts of the world, seasons are based on the amount of rainfall

9. Seasons Winter and Summer Spring and Fall
Earth tilts away from the sun in the winter and towards it in the summer
Because of the Earth’s tilt, the Northern and Southern hemispheres experience opposite seasons
In spring, Earth begins to tilt toward sun, solar energy increases, temperatures rise, and days grow longer
In fall, the opposite occurs

11. Rainfall and the seasons
In the tropics, regions close to the equator, seasons are marked by rainfall rather than temperature
At certain times of the year, winds bring either dry or moist air to the tropics, creating wet and dry seasons

12. Water on Earth
There are two types of water on Earth. What are they?

13. Earth’s Water Water covers 2/3 of the planet
Salt Water
About 97% of the Earth’s water
Unsafe to drink because of high salt levels
In general, found in the Earth’s oceans, which cover about 71% of the Earth’s surface
Also found in some of Earth’s lakes

14. Freshwater Water without salt Makes up only 3% of the water supply
Much freshwater locked in glaciers, large areas of slow moving ice, and in the ice of the Arctic and Antarctic regions
Surface water is found in streams, rivers, and lakes
Less than 1% of the Earth’s water supply

15. Freshwater
Precipitation: water that falls to the Earth as rain, snow, sleet, or hail
Streams form when precipitation collects in narrow channels and flows toward the ocean
Most available freshwater is groundwater, water found below the Earth’s surface
Some naturally bubbles from the ground to the surface as a spring
Most obtained by digging wells

16. Water Cycle
Water circulates from the Earth’s surface to the atmosphere and back again
It is driven by the sun’s energy
Water is the only substance on Earth that occurs naturally as a solid, a liquid, and a gas, or water vapor

18. Water Cycle Evaporation: water turns from liquid to gas
Condensation: rising gas cools and condenses, or changes from a vapor into tiny liquid droplets, to form clouds
Precipitation: if the droplets in the clouds become heavy enough, they fall back to the Earth as rain, snow, sleet, or hail
Runoff: excess water that isn’t absorbed as groundwater flows over land and collects in streams, rivers, and oceans

19. The Role of Water in Our Lives
Water Problems
Water Benefits
Lack of available freshwater
Caused by droughts or overuse
Contaminated, or polluted, water can harm humans, plants, and animals
Flooding can damage property and threaten lives
Provides us with food to eat
Important source of energy
Provides us with recreation, including, swimming, fishing, surfing, and sailing

20. Earth’s Landforms
Landforms: shapes on the planet’s surface, make up the landscapes that surround us
Mountains: land that rises higher than 2000 feet
Valleys: areas of low land located between mountains or hills
Plains: stretches of mostly flat land
Islands: areas of land completely surrounded by water
Peninsulas: land surrounded by water on three sides

21. Earth’s Plates
The planet’s continents, or large landmasses, are part of the Earth’s crust: the solid outer layer of the planet
Theory of plate tectonics: The Earth’s surface is divided into a dozen or so slow-moving plates, or pieces of the Earth’s crust

22. Movement of Continents
Continental Drift: The idea that continents have traveled great distances over millions of years
Theory, developed by Alfred Wegener, states that continents were once united in a single supercontinent and over time, slowly separated and moved to their present positions
As plates collide, separate, and slide, they shape the Earth’s landforms

24. Plate Movement Group activity, pages 37-38 Plates Collide
Define the term. Be sure to describe the cause and effect.
Provide a visual graphic. Be able to draw and explain.
Provide examples
Plates Collide
Plates Separate
Plates Slide

25. Forces on the Earth’s Surface
Weather, water, and other forces change Earth’s landforms by wearing them away or reshaping them
Weathering: Process by which rock is broken down into smaller pieces called sediment
Heating and cooling can cause rock to crack
Expansion as rocks freeze can cause cracks to expand
Roots of trees can pry rocks apart
Erosion: movement of sediment from one location to another
Can wear away or build up landforms

26. Types of Erosion
Wind Erosion lifts sediment into the air and can carry it great distances
On beaches and in deserts, deposits can cause dunes
Blowing sand can wear down rock

27. Glacial Erosion
Glaciers, or large slow moving sheets of ice, erode the land, by carving valleys and mountain peaks
Crush rock into sediment and move it great distances

28. Water Erosion
Waves and flowing water can cut through rock, carry sediment, and deposit sediment in new locations
Floodplains are created when rivers flood their banks and deposit sediment
Sediment carried all the way to the sea creates a delta

29. Landforms Influence Life
Where people settle
What jobs are available
Language
People sometimes change landforms to suit their needs
Examples