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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
Current
Sediments
East Coast
Wave Refraction
Waves bend as they approach a headland
Wave Refraction
Creates
Sea Arches and Sea Stacks
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.
Land's End is the westernmost part of England. The arch is near Cornwall about 10 miles from Penzance .
Copyright ©2005 Bob Fagley
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)
• Controlled by air circulation
Subtropical –• Centered around 30o N and S latitude
• Geographically extensive
Global
Atmospheric
Circulation
Examples: Sahara and Great Australian
Subtropical Desert
Types of Deserts
Continental Interior-• Far from sources of moisture
(ocean)
Example: Gobi in Mongolia
Continental Interior Desert
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.
Example: Coast of Chile and Peru
Coastal Desert
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
Limited amounts of sand
Barchan - wind from one directionStar - wind direction variesLongitudinal - Wind converges from two directions
Abundant sand
Transverse - wind from one directionParabolic – wind blows in land on shores
Sand Dune Summery
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
Limited amounts of sand
Barchan - wind from one directionStar - wind direction variesLongitudinal - Wind converges from two directions
Abundant sand
Transverse - wind from one directionParabolic – wind blows in land on shores
Sand Dune Summery