Flashcards in Coasts-waves Deck (22):
Are Rip currents strong or week?
Strong currents moving away from the coast line.
When do rip currents occur?
They occur when seawater is piled up along the coastline by incoming waves.
The current may run in which direction?
Parallel to the coast before flowing through the breaker zone- possibly at the headland or where the coast changes direction.
Longshore currents occur when?
They occur as most waves do not hit the coastline 'head on' but approach at a angle to the shoreline.
When longshore currents hit the coastline, what do they produce?
Generates a flow of water running parallel to the shoreline.
Where does the water then move to?
The water moves along the surf zone, also transports sediment parallel to the shoreline.
What is the wave height?
The height between a wave crest and neighbouring trough.
What is the wavelength or amplitude?
The distance between successive crests.
What is the wave frequency ?
The time for one wave to travel the distance of one wavelength, or the time between one crest and the following crest passing a fixed point.
What height do constructive waves have?
What wavelength do constructive waves have?
What frequency does constructive waves have?
What happens to swash when constructive waves occur?
Swaths quickly loses volume and energy as water percolates through the beach material.
What wave height does destructive waves have?
High wave height
What frequency does destructive waves have ?
Steep form& high frequency
What happens to destructive waves as they approach the beach?
Rapidly steepen, when break they plunge down.
What type of backwash do destructive waves have?
What effect does destructive waves have on material?
Very little material moved up the beach.
How do upwelling currents begin ?
Movement of cold water from deep in the ocean towards the surface.
What does the more dense cold water do in a upwelling current?
The more dense cold water replaces the warmer surface water.
What does the replacement of cold water do?
Creates nutrient rich cold ocean currents.