Lecture 5 Waves and Currents. Formation of Waves.

Lecture 5 Waves and Currents

Formation of Waves

Travelling Waves

Anatomy of Waves

Forces Generating Waves are Different

Wave type Period Disturbing force Restoring force

Capillary <0.1 sec Wind Surface tension

Forces Generating Waves are Different

Wave type Period Disturbing force Restoring force

Chop 1 – 10 sec Wind Gravity

Forces Generating Waves are Different

Wave type Period Disturbing force Restoring force

Swell 10 – 30 sec Wind Gravity

Forces Generating Waves are Different

Wave type Period Disturbing force Restoring force

Seiche 10 min – 10 hr Wind/Seismic Gravity(standing wave)

Seiche waves

Forces Generating Waves are Different - Summary

Wave type Period Disturbing force Restoring force

Capillary <0.1 sec Wind Surface tension

Chop 1 – 10 sec Wind Gravity

Swell 10 – 30 sec Wind Gravity

Seiche 10 min – 10 hr Wind/Seismic Gravity(standing wave)

Tsunami 10 min – 2 hr Seismic Gravity

Tide 12.4 or 24.8 hr Gravity Gravity

Tsunamis

http://www.youtube.com/watch?v=PBZGH3yieLc&lr=1&feature=mhum

Transition of one wave to another

Worldwide distribution of wave heights

Waves and Depth

Deep water

Shallow water

Breaking Waves

Types of Breaking Waves

Spilling

Result from waves of low steepness (long period swell) over gentle slopes.

Types of Breaking Waves

Plunging

Result from steeper waves over moderate slopes.

Types of Breaking Waves

Surging

Surging breakers surge over steeply sloping (but not vertical) beaches or rocks. Occur where the beach slope exceeds wave steepness.

Gentle – spillingModerate – plungingSteep - surging

Wave breaking

Refraction of Waves

Refraction of Waves

Refraction of Waves

Currents

Currents - Rip currents

Currents - Rip currents

Currents - Coriolis Forces

Currents - Open Ocean

Ekman Spiral

Coastal Upwelling

Coastal Upwelling

Coastal Upwelling - Phytoplankton

Coastal Upwelling - Temperature

Coastal Upwelling - Fishing

Upwelling area Fishing

0.1%

50%

Langmuir Cells

Langmuir Cells

Langmuir cells in sea ice

Deep Ocean Currents

Animation

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Coastlines