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