meteorology- winds and waves Flashcards
What are wind waves and swell waves
Wind waves (sea waves) are generated by the wind blowing at the position considered.
Swell waves are former wind waves that have travelled out of the area of generation or continue in an
area after the wind causing them has ceased.
Waves form in the water surface that reacts with, what?
The airflow
The characteristics of waves depend on what?
The wind speed
Period, seconds, is the time taken between, what?
passage of one crest past a point and the passage of the next crest.
Speed, knots, is what?
the speed of movement of the wave crest through the water.
Speed kts = . x Period s.
3.1
Length, meters is what?
the distance from the crest of one wave to the crest of the next wave.
Height, meters is what
is the vertical distance between crest and trough of a wave.
As wave height increases the shape changes to what?
Trochoidal, with sharper crests and broader troughs
______, _______, _______, and ________ increase as waves grow with increasing wind speed, duration, and
fetch.
height
length
speed
period
Steepness of a wave is the ratio of what
height to length
What is steepness limited by
physical characteristics of water
Waves break at a steepness of approximately what
1:13
The ratios of waves exceeding the average height are:
2x 1:23
3x 1:1175
4x 1:300000
Significant wave height is the average of what?
The highest third of waves
Calm 0
Rippled 0-0._
Smooth 0.1-0._
Slight 0.-1.25
Moderate 1.25-._
Rough 2.5-_
Very rough 4-6
High 6-_
Very high 9-__
Phenomenal >__
1
5
5
2.5
4
9
14
14
Wind wave height varies directly as
- wind speed, governing the energy available for wave generation.
- duration, the length of time over which the sea is influenced by the wind.
- fetch, the distance over which the wind affects the sea.
What does the beaufort scale give
probable and probable maximum wave heights associated with wind force
Swell waves are decreasing in ________ as the viscosity of the water absorbs _______.
magnitude
energy
High waves contain most ______ and have long periods.
energy
Swell wave height decreases and period _________.
increases
Descriptive terms for swell waves.
Length
____ <100m
Average 100—___m
Long >200m
Height
Low <_m
_________ 2-4m
Heavy >4m
short
200
2
moderate
Wind waves and swell waves are named by what?
The direction from which they come
