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