Earth's Physical Geography

1
Unit 2

• Earth's Physical Geography

2
Our Planet, the Earth

• How does the Earth move in space?
• Why do seasons change?

3
The Earth and the Sun

• Days and Nights
• The Earth travels around the sun in an
  oval-shaped orbit.

4

• It takes 365 1/4 days, or one year, for the Earth
  to complete one revolution around the sun.
• As the Earth revolves, it is also spinning on its
  axis.
• Each rotation (or complete spin on the axis)
  takes about 24 hours.
• It is daytime on the side facing the sun and
  night on the side away from the sun.

5
The Earth and the Sun

• Understanding Seasons
• Why are the days longer in some parts of the
  year?
• The Earths axis is at an angle.
• In about half of the Earths orbit, the tilt
  causes a region to face toward the sun for more
  hours than it faces away from the sun.
• Days are longer.
• In other regions that face away from the sun for
  more hours, days are shorter.

6

• Why does the temperature change during the
  seasons?
• The warmth you feel at any given time of year
  depends on how directly the sunlight falls on
  you.
• Some regions receive a great deal of direct
  sunlight, while others receive very little.
• This is also a result of the Earths tilt and
  orbit.

7
Looking at Latitudes
Gets Direct Sunshine on
Line of Latitude
Where is it?
Seasons
8
Zones of Latitudes

9
Looking at Latitudes Zones

• Low Latitudes The Tropics
• Area between the Tropic of Cancer and the
  Tropic of Capricorn
• In this region, it is almost always hot.

10

• Middle Latitudes The Temperate Zones
• Area between the Tropic of Cancer and the Arctic
  Circle
• AND the area between the Tropic of Capricorn and
  the Antarctic Circle
• In this region, there are seasons, each with a
  distinct pattern of daylight, temperature, and
  weather.

11

• High Latitudes The Polar Zones
• Area between the Arctic Circle and the North Pole
  
• AND the area between the Antarctic Circle and the
  South Pole
• In this region it is very cool to bitterly cold.

12
Land, Air, and Water

• What forces shape the land?
• What are the Earths major landforms?

13
Forces Inside the Earth
What is the Earth made of? The Earths surface is
made up of 75 percent water and 25 percent
land. Continents are unique, in part because of
their landforms, which include mountains, hills,
plateaus, and plains.
14

• Pangaea The Supercontinent
• Geographers theorize that millions of years ago
  the Earth had only one huge landmass, which they
  call Pangaea.

15

• They believe that 200 million years ago, some
  force made Pangaea split into several pieces and
  begin to move apart, forming separate continents.

16

• The theory of plate tectonics explains why the
  continents separated.
• Continents are part of plates that shift over
  time.

17
The Movement of the Continents
When geographers first began to study world maps,
they realized that the continents look like
pieces of a jigsaw puzzle.
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
Volcanoes, Earthquakes, and Shifting Plates
The worlds plates move in different directions,
causing a variety of effects Ridges In some
places, plates move apart, and magma leaks
through the cracks in the crust. In the oceans,
over time, the cooling rock builds up to form
lines of underwater mountains called ridges.
22

• Volcanoes In other places, the plates push
  against one another, forcing one plate under the
  other. Tremendous pressure and heat builds up
  causing molten rock to explode on the surface.

23

• Earthquakes
• Along plate boundaries, there are many weak
  places in the Earths crust.
• When plates push against each other, the crust
  cracks and splinters from pressure.
• These cracks are called faults.
• When the crust moves along faults, it releases
  great amounts of energy in the form of
  earthquakes.

24
Forces on the Earth's Surface

• Forces like volcanoes slowly build up the Earth.
  Other forces slowly break it down. These forces
  may not be as dramatic, but they have important
  and long-lasting effects.

25

• The Two Effects of Weathering
• Weathering breaks down rocks into tiny pieces,
  wearing away the Earths landforms. Many
  once-steep mountains are now low and rounded.
  Three things cause weathering wind, rain, and
  ice.
• Weathering helps create soil. Tiny pieces of rock
  combine with decayed animal and plant material to
  form soil.

26

• Erosion
• Once this breaking down has taken place, small
  pieces of rock may be carried to new places by
  erosion. Erosion, together with weathering, help
  slowly create new landforms.

27
Air and Water Two Ingredients for Life

• Air
• The thick layer of gases that surrounds the Earth
  is called the atmosphere.
• It provides life-giving oxygen for people and
  animals and life-giving carbon dioxide for
  plants.
• It also acts as a blanket, holding in enough heat
  from the sun to make life possible.
• Winds distribute this heat around the globe.

28

• Water
• Roughly 97 percent of Earths water is found in
  the oceans.
• The rest is fresh water, or water without salt.
  Most of that is frozen at the poles.
• Fresh water comes from lakes, rivers, and rain.
  Much fresh water, called groundwater, is stored
  in the soil.
• People need fresh waterthe Earth has enough, but
  some places have too much, and others have too
  little.

29
The World Wind Patterns
30
Climate and What Influences It

• What is climate?
• How do landforms and bodies of water affect
  climate?

31
Weather or Climate?

• Weather
• What you check before you go outside in the
  morning
• Day-to-day changes in the air
• Measured primarily by temperature and
  precipitation

32

• Climate
• What you know from experience happens from year
  to year
• The average weather over many years
• The Earth has many climate regions.
• Climates are different in low, middle, and high
  altitudes because latitude affects temperature.
• Landforms, wind, and water also affect climates.

33
The Blowing Winds

• Wind and water help spread the suns heat and
  keep the Earth from overheating.
• Winds blow eastwest and westeast in part
  because of Earths rotation.

34

• Winds blow northsouth and southnorth because
• Hot air rises and circulates toward regions where
  the air is not as hot.
• Hot, moist air from the Equator rises and moves
  toward the North Pole or South Pole.
• Cold air sinks and moves toward regions where the
  air is warmer.
• Cold, dry air from the poles moves toward the
  Equator.

35
Ocean Currents Hot and Cold
The Earths rotation creates ocean currents. Warm
water from the Equator flows north or south to
colder parts and cold water from the poles flows
toward the warm areas near the Equator.
36
The Ocean's Cooling and Warming Effects

• Bodies of water affect climate in another way
  too
• Why is a beach on a hot summer day cooler by the
  ocean?
• Water takes longer to heat or cool than land.
• In the summer, a place near the ocean or a lake
  will be cooler than an area farther away.

37

• The water currents are colder than the air, so
  the current absorbs heat, making the temperature
  fall.
• In the winter, that area will be warmer.
• The water currents are warmer than the air, so
  the current gives off its warmth and the air
  temperature rises.

38
Raging Storms

• Wind and water can make climates milder, but they
  also can create storms. Some storms create great
  destruction.

39

• Hurricanes
• Wind and rain storms that form in the tropics in
  the Atlantic Ocean
• The winds at the center travel over 73 miles per
  hour.
• They produce huge waves called storm surges,
  which flood over shorelines and can destroy homes
  and towns.

40

• Typhoons
• Similar to hurricanes, they take place in the
  Pacific Ocean.

41

• Tornadoes
• Swirling funnels of wind that can reach 200 miles
  per hour.
• The powerful winds can wreck almost anything in a
  tornados path.
• However, they only average about one half mile in
  diameter.
• Therefore they affect a more limited area than
  hurricanes.

42
How Climate Affects Vegetation

• Where are the Earths major climate regions?
• What kinds of vegetation grow in each climate
  region?

43
Climate and Vegetation

• Plants have features, called adaptations, that
  enable them to live in a particular climate.
• Over a very long time, small, accidental changes
  in a few individual plants made them better able
  to survive in a particular place.
• Therefore, geographers can predict the kinds of
  plants they will find in a climate.
• Each climate has its unique vegetation, or plants
  that grow there naturally.

44

• Geographers discuss five broad types of climates
• Tropical
• Dry
• Moderate
• Continental
• Polar

45
Tropical and Dry Climates
Dry Climates
Tropical Climates
46
Moderate Climates
Moderate Climates
47
A Vertical Climate

• A mountain is an example of a vertical climate,
  where the climate changes according to the
  mountains height.
• A hike up a tall mountain in a moderate climate
  would go something like this
• Grasslands surround the base, and temperatures
  are warm.

48

• You soon enter a region with less precipitation
  than belowthere are short grasses, as in a
  continental climate.

49

• Next, you move through deciduous forests where it
  is cooler and drier.
• Slowly the forests change to coniferous forests.

50

• Then, you find only scattered, short trees and
  finally only low shrubs and short grasses.
• Soon it is too cold and dry even for them and you
  begin to see mosses and lichens of a tundra.

51

• At the mountaintop is an icecap climate, with no
  vegetation.