Waves and Tides

Question 1

Density defined by…

Answer 1

Temperature and salinity

Question 2

Nansen bottle

Answer 2

Used for collecting ocean water samples at various depths. It consists of a cylindrical container that sinks vertically through the water column when deployed from a research vessel. Once triggered at a desired depth, the bottle snaps shut, trapping the water sample inside. This sample can then be analyzed in the laboratory for parameters like temperature, salinity, nutrients, and biological content.

Question 3

Wave frequency (f)

Answer 3

= 1/T (time period)

Question 4

Wave slope=

Answer 4

wave height/wavelength
= H/ λ

Question 5

Wave height=

Answer 5

2 λ

Question 6

Orbits of water-parcel in shallow water

Answer 6

Ellipsoids - clockwise

Question 7

Parcel of water in deep water

Answer 7

Round- clockwise

Question 8

Fetch

Answer 8

refers to the distance over which wind blows uninterrupted across the surface of ocean It plays a crucial role in determining the characteristics of waves, influencing their height, length, and energy. Longer fetch distances = in larger and more energetic waves, while shorter fetch distances= smaller waves.

Question 9

Short waves

Answer 9

Travel slower than long waves

Question 10

Outside the fetch where waves sort out each other according to speed

Answer 10

Dispersion

Question 11

Wave generation

Answer 11

Not wind friction associated with laminar flow

Question 12

Laminar flow

Answer 12

Smooth, orderly flow pattern characterized by fluid moving in parallel layers with minimal mixing between them. Fluid particles follow predictable paths, with each layer of fluid flowing at a constant velocity. This type of flow occurs at low velocities and in situations where there is little disturbance or obstruction to the flow.

Question 13

Wavelength spectrum at source

Answer 13

• Large range of wavelengths
• Chaotic

Question 14

Wavelength spectrum at far field

Answer 14

• Smaller range of wavelengths
  Long wavelengths

Question 15

What happens as swell moves from deep ocean to shallow water?

Answer 15

The wave speed changes from the deep water to the shallow water condition: speed becomes controlled not by wavelength but water depth

Question 16

As waves approach the shore

Answer 16

Wave speed decreases as water depth decreases

Question 17

Consequences of waves approaching shore:

Answer 17

• Amplitude increases
• Direction of travel changes due to refraction

Question 18

Huygens Principle

Answer 18

Every point on a wave-front may be considered a source of secondary spherical wavelets. New wavefront defined by tangential to all surfaces

Question 19

Sin(i)/ Sin(e)=

Answer 19

cd/ca

Question 20

As water gets shallower:

Answer 20

Shorter wavelength and larger height

Question 21

As amplitude increases

Answer 21

Shape of wave changes from sine wave to trochoid

Question 22

Trochoid wave

Answer 22

Sharper peak and smoother trough

Question 23

Trochoid

Answer 23

The line traced by a point on the radius of a rolling cylinder

Question 24

When happens to centrifugal force when the distance from the spin axis decreases ?

Answer 24

Centrifugal force increases

Question 24

What causes tides?

Answer 24

Gravitational attraction of the Moon and Sun

Question 25

What happens to gravity when the distance separating the attracting masses increases?

Answer 25

Gravity decreases

Question 26

Centrifugal force

Answer 26

The outward force experience by an object moving in a curved path or rotating around a center point

Question 27

Luni-solar tides

Answer 27

= the result of the combined gravitational forces exerted by both the Moon and the Sun on Earth’s oceans. These tides occur due to the gravitational attraction between the Earth and these celestial bodies.

When the gravitational forces of the Moon and the Sun align, such as during full or new moons when they are in syzygy (aligned with Earth), their combined influence leads to enhanced tidal effects known as spring tides. Conversely, when the gravitational forces of the Moon and the Sun counteract each other, such as during the Moon’s first and third quarters, the tidal range is reduced, resulting in neap tides.

Question 28

Effect of the solid earth being springy

Answer 28

Squashes and stretches in response to tide generating forces

Question 29

Free periods for elastic oscillation

Answer 29

Represent the natural frequencies at which an elastic system vibrates when disturbed and allowed to move freely

Question 30

Amphidromic points

Answer 30

Locations where there are no tidal amplitude

Question 31

Which direction are tides in Northern hemisphere deflected due to coriolis effect?

Answer 31

Right- produces a higher tide on the southern margin

Question 32

Which direction are tides in the Southern hemisphere deflected due to Coriolis effect?

Answer 32

Left- tides rotate counterclockwise around high tides

Question 33

Why does Coriolis effect lead to deflection of tides?

Answer 33

Water is forced to move away from the direction of the gravitational pull of the Moon and the Sun.Difference in eastward velocity