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The Movement of Ocean Water
Currents
Ocean Current movement of ocean water that follows a regular pattern
influenced by:
weather
Earth’s rotation
position of continents
Surface current horizontal movement of ocean water caused by wind
occurs at or near ocean’s surface
controlled by:
global winds
Coriolis effect
continental deflections
Global Winds winds that blow across Earth’s surface that create surface
currents
different winds cause currents to flow in different directions
Coriolis Effect Earth’s rotation causes wind and surface currents to move in a curved path
Continental Deflections
when surface currents meet continents, the currents deflect (change direction)
Taking Temperatures
warm-water currents begin near equator – carry warm water to other parts
cold-water begins close to poles – carry cold water to other parts
Deep Currents stream-like movement of ocean water far below surface
not controlled by wind
forms where water density increases
density affected by: salinity and temp
Increasing Density
Increasing Salinity (Freezing)
cold air chills water, increases density, cold water sinks
when water freezes, salt gets squeezed out at surface and enters liquid below
increases density
Increasing Salinity (Evaporation)
warm climates, water evaporates, leaves salt behind
increases density, sinks to form deep current
Currents and Climate
Surface Currents
Warm-Water Currents that create warm climates in coastal areas that would otherwise be much cooler
Cold-Water Keep coastal areas cooler than inland climate
Upwelling Movement of deep, cold, and mineral-rich water to surface of the ocean
Nutrients support the growth of plankton and animals that eat plankton
El Niño
Effects of El Niño
Change in water temperature in the Pacific Ocean
Produces a warm current
Alters weather patterns
Causes disasters (flash floods, mudslides, droughts)
Prevents upwelling off the coast of South America
Studying El Niño
La Niña
Important due to its effects on land and on organisms
Scientists use a network of buoys along the equator that record data
Cooler than normal temperatures in the Pacific ocean La Niña
El Niño
Waves
Anatomy of a Wave
Wave
Crest
Trough
Made up of crests and troughs
Highest point of a wave
Lowest point of a wave
Wave Formation and Movement
Wave Formation
Wave Movement
Most are formed when the wind blows and transfer its energy to the water
As wind blows, water particles move up and down in circular motion
The water itself stays behind
Specifics of Wave Movement
Wave speed
Wave Period
All waves travel at different speeds
Use an equation to calculate wave speed
Time between the passage of two wave crests (or troughs) at a fixed point
w a v e p e r i o d (s)
w a v e l e n g t h (m) = w a v e s p e e d (m/s)
Types of Waves
Deep-water waves
Shallow-water waves
Move in water deeper than one half their wave-length
When deep-water waves interact with ocean floor
Shore Currents
Undertow
When waves crash on the beach head on
The water moved from this wave flows back into the ocean under the new incoming waves
Movement of water from a shore current moving back into the ocean
Pulls objects with the current
Longshore Currents
Travel near or parallel to the shore line
Form when waves hit the shore at an angle
Transport most of the sediment in beach environments
Open-ocean waves
Whitecaps
Form in the open ocean
2 Types
Whitecaps
Swells
White, foaming waves
Very steep crests
Break in the open ocean before reaching the shore
Swells
Tsunami
Rolling waves that move steadily across the ocean
Form when a large volume of ocean water is suddenly moved up or down
Caused by underwater earthquakes
Storm Surges Local rises in sea level near the shore that are caused by strong winds from a storm
The storm blows water into a big pile under the storm
As the storm moves onto shore, so does the giant mass of water beneath it
Tides
Tide
Daily changes in the level of ocean water
How often a tide occurs and the difference in tide levels depend on the position of the moon as it travels around Earth
The Lure of the Moon
High Tides
Low Tides
When part of the ocean is facing the moon, the water there and on the opposite side of Earth bulges towards the moon
Water is taken from these areas to form high tides
Timing of tides Occur at different times each day because Earth rotates quicker than the moon revolves around Earth
The Sun
Tidal Range
Also effects tides
Combination of sun and moon position in relation to Earth causes tidal ranges
Differences in ocean levels at high and low tides
Tidal Variations
Spring Tide
Neap Tide
Largest daily tidal range
Occur during full and new moons
Sun, Moon, and Earth are aligned
Smallest daily tidal range
Occur during 1st and 3rd quarters of the moon
Sun, Moon, and Earth form a 90° angle
Tidal Bore Occurs in coastal areas with narrow inlets
Body of water rushes up through a narrow bay, estuary, or river channel during the rise of a high tide
Causes a very sudden tidal rise
What is Climate?
Weather
Climate
daily conditions of the atmosphere
temp, wind, precipitation, humidity vary day to day
average weather conditions in an area over time
Latitude
Solar Energy
distance north of south from equator
energy from the sun
hits most directly at the equator; most indirectly at the poles
Seasons seasons change due to the tilt of the Earth’s axis
tilt affects how much solar energy an area receives
near equator and poles have little to no seasonal change
Prevailing Winds
Mountains
winds that blow mainly from one direction
affects precipitation in areas
affects both temperature and precipitation of areas on either side of mountain
Large Bodies of water
Ocean Currents
affects an area’s climate
water absorbs and releases heat slower than land
helps to moderate temp of land around it
surface currents carry warm or cool water to coastal areas
Climate Zones
Biome
three major zones:
tropical
temperate
polar
large zone characterized by climate, types of plants and animals
Changes in Climate
Ice Age
Volcanic Eruptions
long period of climate cooling
ice covered large areas of land
creates shield or dust and ash that block’s sun’s rays and cools climate
Asteroid Impact
Sun’s Cycle
acts like a volcano…throws debris (dust) into air that blocks sun = cools climate
sun follows 11-year cycle
has periods of high and low radiation
Global Warming
Greenhouse Effect
gradual increase in average global temp
natural process
warming of planet due to gases in atmosphere
essential for maintaining temp on surface
Greenhouse Effect
human activities increase gases
gases trap and hold more heat
result: warmer planet and climate changes
carbon dioxide: main contributor to climate change
major greenhouse gases: carbon dioxide, water vapor, methane, nitrous oxide
Consequences of global warming
positive impacts
longer growing seasons
more comfortable climates in cold areas
fewer cold-related deaths
negative impacts rising sea levels (due to melting ice) causing loss of land
more severe weather (hurricanes, tornados, floods, droughts)
species extinction; species unable to adapt to climate changes