coastal systems -sources of energy (tides and currents)

Question 1

what is meant by current?

Answer 1

.refers to the permanent or seasonal movement of surface water in the seas and
oceans

Question 2

how many types of currents are there?

Answer 2

3

Question 3

what are the 3 main types of currents?

Answer 3

.longshore currents
.rip currents
.upwelling currents

Question 4

why do Longshore currents occur?

Answer 4

.because most waves approach the coastline at an angle

Question 5

what happens as a result of Longshore currents?

Answer 5

.a flow of water (current) running parallel to the shoreline -his moves water and transports sediment
parallel to the shoreline

Question 6

what are rip currents?

Answer 6

.strong localised underwater currents that occur on some beaches and move water
away from the shoreline

Question 7

how do rip currents develop?

Answer 7

.develop when waves wash ashore they can pass over obstacles eg -a build up of sand of the sea floor (sand bar), however when the waves wash back out to sea they struggle to pass over the sand bar and so are forced through the gap, this creates a rip current

Question 8

what is an upwelling current?

Answer 8

.movement of cold water from deep in the ocean towards the surface

Question 9

what do upwelling currents form?

Answer 9

.form part of the pattern of global ocean circulation currents

Question 10

what are tides?

Answer 10

.changes in the water level of seas and oceans caused by the gravitational pull of the moon and, to a lesser extent, the Sun

Question 11

what does the moon do to water?

Answer 11

.pulls water towards it, creating a high tide, and there is a compensatory bulge on the opposite side of the Earth
.in areas of the world between the two bulges, the tide is at its lowest

Question 12

what is the tidal range?

Answer 12

.relative difference in height between high and low tides

Question 13

what do tidal ranges determine?

Answer 13

.upper and lower limits of erosion and deposition and the amount of time each day that the littoral zone is exposed to weathering

Question 14

what is the tidal range affected by?

Answer 14

.relative position of the sun and the moon –the highest during the spring tides and the lowest during neap tides

Question 15

what are spring tides?

Answer 15

.when the moon is inbetween the Earth and the sun, the combined gravitational pull creates the biggest bulge of water and the highest tides

Question 16

what are neap tides?

Answer 16

.when the sun, moon and earth form a right angle, the gravitational pulls interfere with one another creating a small bulge of water and the lowest tides

Question 17

what are tidal currents important in?

Answer 17

.in the transfer of sediment within the coastal system or beyond