waves and tides Flashcards
factors that effect wave energy
strength of wind
duration of wind
size of fetch
how does area of low pressure caused
caused by variation in surface heating by the sun. the larger there difference in pressure, the stronger the winds. stronger winds involve stronger waves.
how does the strength of the wind effect wave energy
wind is air that moves from an area of high pressure to low pressure. the difference in pressure difference is caused by variations in surface heating by the sun. the larger the difference in pressure, the stronger the winds, therefore the stronger the waves.
how does the duration of the wind effect wave energy
if the wind is active for longer periods of time, the energy of the waves will build up and increase.§
how does the size of the fetch effect wave energy.
the larger the distance the waves can flow, then there can be more energy created in the waves therefore the stronger the waves.
constructive waves?
build up depositional landforms
destructive waves?
remove depositional landforms§
features of constructive waves
formed by weather systems that are operated in the ocean.
long wavelengths
6-9 frequency per minute
low waves which surge up the beach
strong swash, weak backwash
occurs on gently sloped beaches
features of destructive waves
localised ström events that happen closer to the coast
short wavelength
11-16 frequency per minute
high waves, that plunge onto the beach
weak swash, strong backwash
occurs on steeply sloped beaches
what’s responsible for tides
gravity
tidal range
the difference in heights of tides.
spring tides
occur when the sun moon and earth are in alignment.
both gravitational forces combine and pull the ocean towards them. on the other side of the earth, this creates the lowest possible tides.
this creates the biggest possible tidal range.
neap tides
the lowest possible tide range occurs when the sun and moon are perpendicular to each other.
both gravitational forces act against against Rach other, so the pull is minimalist at low tide but is higher at low tide.
this creates the smallest possible tidal range.
marine erosional processes
corrosion
abrasion
attrition
hydraulic action
corrasion
wave quarrying
wave quarrying
similar to hydraulic action, except more pressure
exert a pressure up to 30 tonnes
hammers the rock surface
corrosion (solution)
mildly acidic seawater causes alkaline rocks, such as limestone, to be eroded via carbonation weathering.
hydraulic action
air is forced into cracks and joints, and the high pressure causes the cracks to widen, when the waves push in and out of the cracks. over time this causes the rocks to widen.
whats cavitation.
bubbles in the water implode under high pressure, creating tiny jets that erode the rock.
what are tides
tides are changes in the water levels of seas and oceans caused by gravitational pull of the moon and to a lesser extent the sun.
how do tides effect the coastal environment
the coastline experiences two high and low tides each day. the relative difference is called the tidal range.
spring tides
spring tides are caused when the sun moon and earth are in alignment. this creates the strongest pull, and causes the highest possible tide. therefore resulting in a spring tide.
high energy coast features
long fetch
consistency strong waves
landforms such as caves arches etc
significant erosion and substantial transportation.
driven by prevailing wind
imputs energy into system from many sources
what are neap tides
neap tides occur within the first quarter and third quarter of the moon. it occurs when the moon and sun are perpendicular to each other. this therefore means that their gravitational pull isn’t aligned therefore isn’t as strong. this means that the bulge isn’t as big, therefore resulting in a lower higher tide and a higher lower tide. this is known as a neap ride
low energy coast features
waves less powerful
tidal currents relatively gentle
landforms such as spits, sandunes
associated with deposition
sediment from rivers and LSD - fine sediments slow things down.
why do tidal ranges differ throughout the uk
due to the morphology of the seabed and the coastline.
