The Oceans
Ocean-Atmosphere Links
Exchange of water, carbon dioxide
(gases) and heat.
Surface currents are driven by
atmospheric circulation.
Surface
Currents
Surface Currents
Transfer heat from one place to
another.
Keep the upper 100 meters of the
ocean well mixed.
The Ocean is Stratified
Oceans and Climate
Heat transferred from the Equator
towards the poles.
Example: England has a relatively
warm climate at a latitude of
Northern Canada.
Thermohaline
Circulation
Thermohaline Circulation
Driven by Density Differences,
difference in temperature and salinity.
Completes cycle in 6 yrs.
Waves
move
energy, not
water
Important
Parts
Wave length
Crest
Trough
Breakers
Waves break when wave base = ½ wave length
Rip Current (Rip Tide)
Longshore Sediment Transport
Barrier Islands
Barrier Islands
East Coast
Sediments
Current
Wave Refraction
Waves bend as they approach a headland
Wave Refraction
Creates
Sea Arches and Sea Stacks
Land's End is the
westernmost part of
England. The arch is
near Cornwall about 10
miles from Penzance .
Copyright ©2005 Bob Fagley
This great double arch is in the
Shetland Islands. The Islands, are the
northernmost outposts of the United
Kingdom and lie N.E. of northern
Scotland.
Copyright ©2005 Bob Fagley
Tides
Tides
Tides
Tides
Deserts
What is a desert?
Less than 250 mm (10 inches) of
precipitation.
Generally lacking in vegetation.
Cannot support a large population ??
Types of Deserts (5)
Subtropical –
• Centered around 30o N and S
latitude
• Controlled by air circulation
• Geographically extensive
Global
Atmospheric
Circulation
Troposphere
30o
Latitude
Warm wet air
rises. It cools
and it rains
Hadley Circulation Cell
Ground or Ocean
Equator
Cold dry air falls.
As it warms it begins
evaporating moisture
Subtropical Desert
Examples: Sahara and Great Australian
Types of Deserts
Continental Interior• Far from sources of moisture
(ocean)
Continental Interior Desert
Example: Gobi in Mongolia
Types of Deserts
Rainshadow• Mountain ranges cause barrier
to flow of moisture.
Rainshadow Desert
Examples: Cascades and Sierra Nevada
Types of Deserts
Coastal Desert • Cool dry air blows in from the ocean
and evaporates occurs as it warms.
Coastal Desert
Example: Coast of Chile and Peru
Types of Deserts
Polar –
• Cold air holds very little moisture.
• What little precipitation falls
remains as ice for 1000's of years.
Examples: Greenland and Antarctica
Erosion by Wind
Abrasion – airborne particles chip off
small fragments of other rocks.
Ventifacts
Erosion by Wind
Deflation – removal of small, loose
particles. Can form desert pavement.
Deposition by Wind
Dune – hill or ridge of sand deposited
by winds.
Dune Types
Dependent on:
• Sand supply
• Wind velocity
• Variability of wind direction
• Surface over which the dune
moves
Sand Dune Summery
Limited amounts of sand
Barchan - wind from one direction
Star - wind direction varies
Longitudinal - Wind converges from two directions
Abundant sand
Transverse - wind from one direction
Parabolic – wind blows in land on shores
Barchan - Sand is limited, steady wind from
one direction
Longitudinal (Linear) - Limited sand
supply, strong converging winds
Star - Sand scarce, wind shifts
Transverse - Abundant sand, moderate wind
Parabolic - Abundant sand, strong offshore
wind
Sand Dune Summery
Limited amounts of sand
Barchan - wind from one direction
Star - wind direction varies
Longitudinal - Wind converges from two directions
Abundant sand
Transverse - wind from one direction
Parabolic – wind blows in land on shores