The motion of the ocean Flashcards
what determines the size of a wave
wind speed, duration and fetch
how does the energy of a wave dissipate
friction
what is stokes drift
the small net flow of water causes by a wave
does energy increase or decrease with depth
decrease
when will you stop feeling a wave
at half the wave length deep
what is the wave base
half the wave length deep, the effective lower limit of wave motion
what is a fully developed sea?
wave energy in = wave energy out
what is surf
the wave activity between the line of breaking waves and the shore
at what depth do waves usually break
wave height depth or 1.5 x wave height depth
what is wave refraction
change in direction of a series of waves moving in shallow water at an angle to the shoreline. Due to trend of breaking wave becoming realigned to parallel bottom contours of the bed
how is a longshore current created
incoming wave resolved in two directions due to refraction: perpendicular and parallel to the shore
what is the dissipated energy from waves used for
erosion and transport
what factor impacts the energy dissipation and therefore amount of erosion?
nature of the seafloor gradient
what is the time interval between wave peaks called
period
what is the number of peaks per second called
frequency
what are capillary waves
short wavelengths with rapid periods
which two forces are balanced in tides
inertial and gravitational
explain how the tides are formed
water on side of earth nearest the moon is pulled by gravity, this creates a bulge of water. Inertia keeps objects moving straight ahead away from the centre of the earth-moon system (works against gravity). Inertia equal at all points. On the moon side, gravity exceeds inertia, causing the tide. Water from poles drawn to the equator
explain the spring and neap tides
sun has smaller gravitational pull. when it lines up with the tidal bulge of the moon we get spring tide. When the bulges are at opposite sides (sun and moon at right angles) we get neap tide.
what is submergence
rise of water in relation to the land
what is emergence
lowering of water in relation to the land
what is the main cause of emergence or submergence
glaciers melting or building up
what is the main cause of local emergence and submergence
tectonic activity
how much higher would sea levels be if all ice on land melted entirely
65-80m
what impacts would melting sea ice have
not a dramatic impact on sea levels as its already in the sea, but would decrease salinity and impact thermohaline circulation
name 6 ways that the ocean is important to humans
energy (oil from rocks and renewable hydro energy), food, employment, undersea mining, transport for goods and people, climate moderation
