Section 2: Coastal processes equations Flashcards
Wave celerity (speed)
C = L/T
What are the forces in wave celerity equation
L is wavelength
T is wave period
Deep water wave celerity
Depth: D >L/2
C = gT/2π = √ gL/2π
What is Hb (little b)
Wave height at breaking
What is hb (little b)
Wave depth at breaking
Shallow water wave celerity
Depth: D<L/20
C = √gD
L = T √gD
Celerity is only dependent on water depth in shallow water
What is the approx. wave depth in relation to breaking wave height
Hb = 0.78hb
Distance =
speed x time
Celerity =
distance / time
Time =
distance / celerity
Irribarren number equation
ξ = tanβ / √Hb / Lo
What does the Irribarren number show
Wave breaking control, surf similarity parameter
C0 (little 0)
= 0.56T
L0 (little 0)
= 1.56T^2
What is the Universal Law of Gravitational Attraction
The force of gravitational attraction (F) of two particles of masses M1 and M2 separated by a distance r
Universal Law of Gravitational Attraction equation
F = GM1M2/ r^2
What is the universal gravitational constant
G= 6.67 x 10^11 Nm^2/kg^2
Change in sea surface level equation
Δζ = -ΔPA / (ρg)
What are the forces in sea surface level equation
* finish*
Δζ is change in sea surface level
-ΔPA is change in local air pressure
Inverse barometer effect equation
Δζ ~ 1ΔPA
A 1mbar rise (/fall) of air pressure is equal to
1cm rise (/fall) in sea level
Change in sea level with distance equation
dζ / dx = τ /gρD
What are the forces in change in sea level equation
In equilibrium, the wind stress must balance the pressure gradient caused by a slope in the sea surface ( dζ / dx in cm)
τ is wind stress
g is gravitational acceleration
ρ is water density
D is water depth
Slope is inversely proportional to depth- only in shallow sea that a major change in sea level expected
Tide generating force
P = 2G (mpm1a / r^3)
2mp (m1/m2)* (a/r)^3
Tidal generation force is proportional to the mass of the Moon and inversely proportional to the cube of the distance between the Earth and moon