The Oceans
Ocean-Atmosphere Links Exchange of water, carbon dioxide (gases) and heat. Surface currents are driven by atmospheric circulation.
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
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
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
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 30 o 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 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 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 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 Sand Dune Summery