35 Waves

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3-5 Waves (Earth Book)
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How Waves Form
Energy in waves comes from wind that blows across
the waters surface!
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Wave Motion
Wave Motion 2
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• As the wind makes contact with the water, some of
  its energy transfers to the water
• Water particles move up and down, NOT forward
  the form of the wave moves forward
• As wave approaches land, the water particles DO
  move forward
• Forward-moving water shapes the coast

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Erosion by Waves
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Impact Energy in waves can break apart rocks
make cracks larger
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Abrasion As a wave approaches shallow water,
it picks up sediment, when the wave hits land,
the sediment wears away rock like sand paper
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Landforms created by Wave Erosion
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Wave-cut cliff
Waves erode base of the land so much that the
rock above collapses
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Headland
Part of the shore that sticks out into the ocean
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Headland
Waves coming to shore change direction bend to
concentrate their energy on the
headland Eventually wears it down evens out the
shore
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Sea Cave
When a soft pocket of rock surrounded by harder
rock is hollowed out by wave erosion, usually in
a headland
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Inside a Sea Cave
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Sea Arch
When a soft pocket of rock is hollowed right
through a headland to the other side, usually a
sea arch is created from a sea cave
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Sea Stack
When the top of a sea arch collapses, a pillar of
rock is left behind
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Deposition by Waves
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Beach
An area of wave-washed sediment along a
coast. Sediment usually sand from rivers, but
also coral or seashell bits
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Longshore Drift
Waves coming into a beach come in at an angle not
straight on
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Creates a current that is parallel to shore.
Thats why they say if you get stuck in the
under toe swim parallel to shore
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Longshore Drift Sediment build-up
Moves sediment down a beach in the direction of
the current
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Spit
A beach that projects from the shore like a
finger as longshore drift carries sediments down
a beach, the sediments get deposited when they
run into a headland or other obstacle
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Sandbar
Long ridges of sand parallel to the shore Built
up by incoming waves
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Barrier Beach
Similar to a sandbar Formed when storm waves pile
sand above sea level Dangerous to live on-can be
swept away by a storm
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2-3 Winds (Weather Book)
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What is Wind?

• Horizontal movement of air from an area of high
  pressure (H) to an area of lower pressure (L)
• The greater the difference, the faster the wind
  moves
• Differences in air pressure are caused by the
  uneven heating of Earth
• Described by direction coming from speed

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What is Wind?
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LOCAL WINDS

• Move short distances
• Can blow in any direction
• Caused by unequal heating of Earths surface
  within a small area

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SEA BREEZE

• Land heats up fast during day (low pressure)
• Ocean stays cool (high pressure)
• Uneven heating creates wind
• H?L
• Ocean ? Land
• Air moves from the ocean to the land creating a
  sea breeze

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SEA BREEZE
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LAND BREEZE

• Land cools down colder than ocean at night (high
  pressure)
• Ocean stays warmer than land (low pressure)
• Uneven heating creates wind
• H?L
• Land ? Ocean
• Air moves from the land to the ocean creating a
  land breeze

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LAND BREEZE
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GLOBAL WINDS

• Winds that blow steadily from specific directions
  over long distances
• Caused by unequal heating of Earths surface over
  large areas

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Non-Rotating Earth Model

• On a hypothetical non-rotating planet, 2 large
  wind currents would form.

Northern Hemisphere Southern Hemisphere
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Non-Rotating Earth Model
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Rotating Earth Model

• When the effect of rotation is added, the 2 cells
  would break into many smaller cells (wind belts).

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Coriolis Effect

• As Earth rotates, the Coriolis Effect turns winds
  in the Northern Hemisphere toward the right.

Rotation of earth
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Coriolis Effect
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Global Wind Belts

• A series of wind belts circle Earth. Between the
  wind belts are calm areas where air is rising or
  falling.

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• Global Wind Belts
• Doldrums Horse Latitudes very weak winds,
  almost no winds, located at the equator
• 00 (doldrums) and 300 (horse latitudes).
• 2. Tradewinds Located 00 to 300N 300S of the
  equator. Winds are very calm, warm and steady.
• 3. Prevailing Westerlies Strong winds located
  300-600 latitude in both hemispheres. Travel west
  to east.
• 4. Polar Easterlies Cold, but weak winds
  located 600 to the poles
• 5. Jet stream Strong, belt of high-speed,
  high-pressured winds. Blow from west to east.

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3-6 Wind (Earth Book)
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WIND EROSION
Weakest agent of erosion Shapes land in areas
with few plants to hold soil in place
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D E F L A T I O N
Process by which sand removes surface materials
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D E F L A T I O N
Fine particles- carried through the air (clay
silt) Medium particles-skip, bounce or jump
(sand) Large particles-slide or roll (pebbles
rocks)
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Desert Pavement
When all the smaller sediments (clay, silt, sand)
are removed and only larger rocky materials too
heavy or large to move remain
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Slight depression in the ground, deflation can
create a bowl-shaped hollow
Blowout
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WIND DEPOSITION
When wind slows down or hits an obstacle,
sediments are dropped (deposited)
The stick in the picture acts as a wind obstacle.
It lowers the wind speed and allows for sand to
build up behind the stick.
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Beach Sand Dune
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Desert Sand Dune
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Sand Dune

• Coarse wind-blown sediment that has built up
• Happens when wind hits an obstacle (clump of
  grass/rock)
• Seen on beaches and in deserts
• Many shapes and sizes
• Move over time shifting from one side to another
• Plant roots can anchor a dune (help keep it in
  place)

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Loess deposit layer
Fine, wind deposited sediments

• Clay or silt
• Deposited in layers
• Can travel far from source
• Help form fertile soil (valuable farm land)

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Major loess deposits in the U.S.