Chapter 6

Question 1

Internal waves

Answer 1

gravity waves that oscillate within a fluid medium, rather than on its surface

Question 2

to be existence of internal waves the ….. must be …..

Answer 2

fluid must be stratifies: the density must decrease continuously or discontinuously with height due to changes in temperature

Question 3

if the density changes over a small vertical distance (…….) the wave

Answer 3

(as in the case of an atmospheric inversion) the wave propagate horizontally like surface waves, but do so at slower speeds as determined by the density difference of the fluid below and above the interface.

Question 4

If the density changes continuously, the

Answer 4

waves can propagate vertically as well as horizontally through the fluid

Question 5

internal gravity waves go by many other names depending on

Answer 5

• the fluid stratification
• generation mechanism
• amplitude
• influence of external forces

Question 6

Interfacial (internal) waves

Answer 6

if propagating horizontally along an interface where the density rapidly decreases with height

Question 7

Internal solitary waves

Answer 7

if the interfacial waves are large amplitude

Question 8

anelastic internal waves

Answer 8

if moving vertically through the atmosphere where substantial change in air density influences their dynamics

Question 9

Lee waves

Answer 9

(mountain waves)

If generated by flow over topography

(standing waves)

Question 10

Chinook winds

Answer 10

(chinook winds in north america or Foehm winds in Europe (Alps))

if the mountain waves break aloft, they can result in strong warm winds at the ground

(warm winds)

Question 11

Internal tides

Answer 11

if generated in the ocean by tidal flow over submarine ridge or the continental shelf

Question 12

inertia gravity waves

Answer 12

if they evolve slowly compared to the earth’s rotational frequency so that their dynamics are influenced by the corriolis effect

Question 13

internal waves are usually distinguished from rossby waves, which are influenced by

Answer 13

the change of coriolis frequency with latitude

Question 14

examples of atmospheric internal waves:

Answer 14

• wave clouds
• herringbone sky or meckerel sky
• internal solitary waves

Question 15

Wave clouds:

Answer 15

at the wave crest air rises and cools in the relatively lower pressure, which can result in water vapor condensation if the relative humidity is close to 100%. clouds that reveal internal waves launched by flow over hills are called lenticular clouds because of their lens-like appearance

Question 16

mackerel sky

Answer 16

less, dramatically, a train of internal waves can be visualized by rippled cloud patterns

Question 17

Internal solitary waves

Answer 17

the outflow of cold air from thunderstorms can launch large amplitude internal solitary waves at an atmospheric inversion. these waves span many hundred of kilometers.

Question 18

The Brunt–Väisälä frequency (buoyancy frequency) is

Answer 18

the angular frequency at which a vertically displaced parcel will oscillate within a statically stable environment.

Question 19

The Brunt–Väisälä frequency (buoyancy frequency) is the angular frequency at which a vertically displaced parcel will oscillate within a statically stable environment. It can be used as a measure of

Answer 19

atmospheric stratification.

Question 20

where quantities with a ‘~’ character are

Answer 20

properties of the air parcel

Question 21

those with an overbar are for the

Answer 21

surrounding environment

Question 22

As parcels rise and expand their

Answer 22

pressure instantaneously adjusts to be equal to that of the surrounding environment

Question 23

N²

Positive:

Negative:

N

Answer 23

Imaginary

real

Question 24

N2

Positive:

Negative:

solutions for z(t)

Answer 24

oscillations

exponentially

Question 25

N2

Positive:

Negative:

static stability

Answer 25

stable

unstable

Question 26

If we ignore changes in density due to local compression or expansion, which is a valid assumption as long as

Answer 26

the waves are short compared to the scale at which the density changes with height (large values of wave 4 number).