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Chapter 2 Earth and the Sun

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Title: Chapter 2 Earth and the Sun


1
Chapter 2Earth and the Suns Energy
  • The Big Idea
  • Earths movement and the suns energy interact to
    create day and night, temperature changes, and
    the seasons.
  • Main Ideas
  • Earths movement affects the amount of energy we
    receive from the sun.
  • Earths seasons are caused by the planets tilt.

2
Earths movement affects the amount of energy we
receive from the sun.
  • All life on Earth requires solar energy, or
    energy from the sun, to survive.
  • Amount of solar energy received changes
    constantly
  • Earths rotation, revolution, tilt, and latitude
    all affect the amount of solar energy Earth
    receives.

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Rotation
  • Earth spins on its axis an imaginary line that
    runs through the center of the planet around
    which it turns.
  • It takes Earth 24 hours to make one rotation, or
    complete spin on its axis.
  • As Earth spins, different parts of the planet
    face the sun, thus 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 Earth 365¼ days to complete one
    revolution, or trip around the sun.
  • Our calendar year is based on the time it takes
    Earth to complete its orbit.

6
Tilt
  • Tilt
  • Earths axis is tilted at an angle of 23½ degrees
    from vertical.
  • At any give time of year, 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
  • Latitude is the distance north or south of
    Earths equator.
  • Low-latitude areas, those nearest 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
Questions of the Day
  • What is solar energy?
  • How does the Sun affect life on Earth?
  • What four things affect the amount of sunlight we
    receive?
  • Take the next 5 minutes in class to answer these
    questions.
  • Refer back to your notes for help!

9
Earths seasons are caused by the planets
tilt.
  • Seasons are periods during the year that are
    known for a particular type of weather.
  • Many places experience four seasons winter,
    spring, summer, and fall.
  • In some parts of the world, seasons are based on
    the amount of rainfall

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Summer
  • Earth tilts towards the sun in summer.

12
Winter
  • Earth tilts away from sun in winter

13
Spring and Fall
  • In spring tilt toward sun, solar energy
    increases, temperatures rise, and days grow
    longer.
  • In fall tilts away from sun, solar energy
    decreases, temperatures decrease, days are
    shorter

14
Tropics
  • Tropics seasons are marked by rainfall rather
    than temperature.
  • Monsoons, winds bring either dry or moist air to
    the tropics, creating wet and dry seasons.

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The Seasons
  • Winter and Summer
  • Earth tilts away from sun in winter and towards
    the sun in summer.
  • Because of the Earths tilt, the Northern and
    Southern hemispheres experience opposite seasons.
  • Spring and Fall
  • In spring, Earth begins to tilt toward sun, solar
    energy increases, temperatures rise, and days
    grow longer.
  • In fall, the opposite occurs.
  • Rainfall and Seasons
  • In the tropics, regions close to the equator,
    seasons are marked by rainfall rather than
    temperature.
  • At certain times of year, winds bring either dry
    or moist air to the tropics, creating wet and dry
    seasons.

17
Water on Earth
  • Water is a dominant feature on Earths surface
    and is essential for life.
  • Salt water and freshwater make up Earths water
    supply.
  • In the water cycle, water circulates from Earths
    surface to the atmosphere and back again.
  • Water plays an important role in peoples lives.

18
Salt water and freshwater make up Earths water
supply.
  • Water covers some two-thirds of the planet.

Earths Water
  • About 97 percent of the Earths water
  • Unsafe to drink because of high levels of salt
  • In general, found in Earths oceans, which cover
    some 71 percent of the planets surface
  • Also found in some of Earths lakes

Salt Water
  • Water without salt
  • Makes up only 3 percent of our water supply

Freshwater
19
Freshwater
  • Much of Earths freshwater is locked in glaciers,
    large areas of slow moving ice, and in the ice of
    the Arctic and Antarctic regions.
  • Surface water is water that is found in Earths
    streams, rivers, and lakes.
  • Less than one percent of Earths water supply
  • Streams, rivers, and lakes are common sources.
  • Precipitation is water that falls to Earths
    surface as rain, snow, sleet, or hail.
  • Most available freshwater is groundwater, water
    found below Earths surface.
  • Some naturally bubbles from the ground to the
    surface as a spring.
  • Most obtained by digging wells

20
The Water Cycle
  • Water is the only substance on Earth that occurs
    naturally as a solid, a liquid, and a gas, or
    water vapor.
  • The water cycle is the movement of water from
    Earths surface to the atmosphere and back it
    is driven by the suns energy.
  • Evaporationwater turns from liquid to gas.
  • Condensation the rising gas cools and condenses,
    or changes from a vapor into tiny liquid
    droplets, to form clouds.
  • Precipitation if the droplets in clouds become
    heavy enough, they fall back to Earth as rain,
    snow, sleet, or hail.
  • Runoff excess water that isnt absorbed as
    groundwater flows over land and collects in
    streams, rivers, and oceans.

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Water plays an important role in peoples lives.
  • Water Problems
  • Lack of available freshwater, which can be
    caused by droughts or overuse
  • Contaminated, or polluted, water can harm humans,
    plants, and animals.
  • Flooding can damage property and threaten lives.
  • Water Benefits
  • Provides us with food to eat
  • Important source of energy
  • Provides us with recreation, including swimming,
    fishing, surfing, and sailing

23
The Land
  • Processes below and on Earths surface shape the
    planets physical features.
  • Earths surface is covered by many different
    landforms.
  • Forces below Earths surface build up our
    landforms.
  • Forces on the planets surface shape Earths
    landforms.
  • Landforms influence peoples lives and culture.

24
Earths surface is covered by many different
landforms.
  • Landforms, or shapes on the planets surface,
    make up the landscapes that surround us.
  • Earths surface is covered with landforms of many
    different shapes and sizes.
  • Mountains, land that rises higher than 2,000 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

25
Forces below Earths surface build up our
landforms.
Earths Plates
  • The planets continents, or large landmasses, are
    part of Earths crustthe solid outer layer of
    the planet.
  • Theory of plate tectonics suggests that Earths
    surface is divided into a dozen or so slow-moving
    plates, or pieces of Earths crust.

Movement of Continents
  • The idea that continents have traveled great
    distances over millions of years is known as
    continental drift.
  • Theory, developed by Alfred Wegener, states that
    the 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 Earths landforms

26
Plates Collide, Separate, and Slide
  • Plates Collide
  • Two ocean plates one pushes under the other,
    creating ocean trenches, or deep valleys in ocean
    floor
  • Ocean and continental plate ocean plate drops
    beneath continental plate, forcing land above to
    crumple and form mountain range
  • Two continental platesland pushes up to form
    mountains
  • Plates Separate
  • As plates move apart, gaps between plates allow
    magma to rise to Earths crust.
  • Lava, magma that reaches the Earths surface,
    emerges from the gap.
  • As lava cools, it builds a mid-ocean range, or
    underwater mountain, that can rise above the
    surface of the ocean to form islands.
  • Plates Slide
  • As plates pass by each other, they sometimes
    grind together, producing earthquakes, sudden,
    violent movements of Earths crust.
  • Earthquakes often take place along faults, or
    breaks in Earths crust where movement occurs.
  • The region around the Pacific plate, called the
    Ring of Fire, is home to most of the worlds
    earthquakes and volcanoes.

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Forces on the planets surface shape Earths
landforms.
  • Weather, water, and other forces change Earths
    landforms by wearing them away or reshaping them.
  • Weathering is the process by which rock is broken
    down into smaller pieces called sediment.
  • Heating and cooling can cause rocks to crack.
  • Expansion of water as it freezes can cause cracks
    to expand.
  • Roots of trees can pry rocks apart.
  • Erosion is the movement of sediment from one
    location to another.
  • Can wear away or build up landforms

31
Types of Erosion
  • Wind Erosion
  • Winds lift sediment into air and carry it across
    great distances .
  • On beaches and in deserts, deposits can form
    dunes.
  • Blowing sand can wear down rock.
  • 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
  • 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 by a river all the way to the
    sea creates a delta.

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