Waves

Question 1

How waves form

Answer 1

• up and down movement of ocean surface caused by wind
• pushes surface, lifting surface
• size = wind speed + duration of wind + distance over which it blows
• biggest wave; 1933 USS Ramapo, 34 meters high (112 feet)

Question 2

Parts of a wave

Answer 2

• Crest – top of wave
• Trough – bottom of wave
• Height – distance from crest to trough
• Wavelength – distance b/w crests or troughs
• Period – time it takes a wave to pass a fixed point
• Fetch – span of water across which the wind blows

Question 3

Rogue waves

Answer 3

• crests of different waves meet; double the energy and possibly the height
• caused by focusing by currents — storm forced waves are driven into an opposing current, results in shortening of wavelength, causing an increase in wave height and oncoming wave trains to compress together into a rogue wave

Question 4

Tsunamis

Answer 4

• Caused by earthquakes, underwater landslides and volcanos
• 150mile wavelength, 400mph
• As the wave approaches land, the sea shallows
  the wave no longer travels as quickly, so it begins to “pile-up”; the wave-front becomes steeper and taller, and there is less distance between crests
• Mostly occurring in Pacific (lots of seismic activity)
• E.g. Thailand Tsunami: Resulted from a 9.3 scale earthquake, second largest in recorded history