EAE2111 - Topic 2 - Wk 2 Flashcards

Question 1

Q

What is temperature advection?

Answer

A

Advection occurs when the isobars (lines of constant pressure) do not align with the isotherms (lines of constant temperature).

Cold fronts, or those warm North-westerlies that precede them are excellent examples of why we care about the temperatures that are carried (advected) by surface winds._{EAE2111 2aa}

Question 2

Q

What is required for formation of fronts?

Answer

A

<div>Formation of fronts requires two main things: </div>

<ul> <li>Two distinct air masses that are distinct sit adjacent to one another. </li> <li>Winds that bring the air masses together.</li></ul>

_{EAE2111 2ab}

Question 3

Q

Air Masses

pTm

Answer

A

Tropical maritime Pacific

<div>Warm and moist.</div>

_{EAE2111 2ac}

Question 4

Q

Air Masses

tTm

Answer

A

Tropical maritime Tasman

<div>Warm, unstable and moist to high levels.</div>

_{EAE2111 2ad}

Question 5

Q

Air Masses

Sm

Answer

A

Southern Maritime

<div>Generally cool moist air, unstable at low levels and stable aloft.</div>

_{EAE2111 2ae}

Question 6

Q

Air Masses

NPm

Answer

A

modified Polar maritime

<div>Generally cold, moist and unstable</div>

_{EAE2111 2af}

Question 7

Q

Air Masses

Em

Answer

A

Equatorial maritime

<div>Gneral very warm and moist.</div>

_{EAE2111 2ag}

Question 8

Q

What are frontogenesis?

Answer

A

Frontogenesis occurs where there is a concentration of isotherms with the circulation to sustain that concentration.

_{EAE2111 2ah}

Question 9

Q

What is frontolysis?

Answer

A

The dissipation of a front

<div>occurs when either: </div>

<ul> <li>The temperature difference between the two air masses disappears </li> <li>The wind carries the air masses away from each other</li></ul>

_{EAE2111 2ai}

Question 10

Q

Describe

Cold Front

Answer

A

Cold Front is characterized by a cold (more dense) air mass is moving into a warmer (less dense) air mass. Characterized by abrupt uplift along the frontal boundary._{EAE2111 2aj}

Question 11

Q

Describe

Warm front

Answer

A

<div>Warm Front is characterized by a warm (less dense) air mass moving into a cold air mass. </div>

<div>These are relatively rare in Australia.</div>

_{EAE2111 2ak}

Question 12

Q

What is the Ekman spiral?

Answer

A

<ul><li>Surface friction slows down winds, as you move towards the surface the winds veer to the right in the Southern Hemisphere (SH) and to the left in the Northern Hemisphere (NH). </li><li>A similar effect is observed in the ocean. Each layer of the ocean drives the layer below through surface friction. </li><li>As this is an acceleration (rather than a slow down) the oceanic Ekman spiral veers to the left in the SH (right in the NH) with depth.</li></ul>

_{EAE2111 2al}

Question 13

Q

What is Ekman transport?

Answer

A

<ul> <li>Ekman induced upwelling leads to cooling of the surface waters due to the raising of deeper, normally nutrient rich, subsurface waters.</li> <li>Occurs in the SH when the winds blow from left to right when standing on the beach looking at the ocean.</li></ul>

<ul> <li>Ekman transport generates regions of high and low ocean pressure.</li> <li>It can also create regions of upwelling and downwelling, particularly when near an ocean boundary or near the equator.</li></ul>

_{EAE2111 2am}

Question 14

Q

What is geostrophic transport?

Answer

A

<ul><li>Flow in the upper ocean, off the equator, is largely geostrophic (a balance between PGF and coriolis force). </li><li>Anti-clockwise flow in the Southern Hemisphere and clockwise flow in the northern Hemisphere.</li></ul>

_{EAE2111 2an}

Question 15

Q

What are the impacts of the western boundary currents?

Answer

A

<ul><li>Strong western boundary currents lead to strong temperature advection</li><li>Also have a chaotic component</li><li>Generally considered less dominant than in the atmosphere</li></ul>

_{EAE2111 2ao}

Question 16

Q

What are thermally direct circulations?

Answer

A

<ul> <li>Cooler air temperatures generate lower pressures aloft</li> <li>Air over cooler surface has higher pressure relative to warm surface</li> <li>Air at the surface moves from high to low pressure, towards the warm surface</li> <li>Causes low pressure relative to surrounding air</li> <li>Air aloft moves from high to low pressure, towards the cool surface</li></ul>

<div>→ Back to beginning </div>

_{EAE2111 2ap}

Question 17

Q

What is the energy balance for land and sea breezes?

Answer

A

<ul> <li>Land-sea differences in Rₙ are only of secondary importance</li> <li>Low albedo over sea during much of the day means more energy is absorbed</li> <li>However, there are major differences in the way Rₙ is partitioned to the environment over land and water</li></ul>

<div>Day: Air overlying the land becomes much warmer than that overlying the water </div>

<div>Night: Warmer air over the water</div>

_{EAE2111 2aq}

Question 18

Q

Describe

Sea and land breeze circulations

Answer

A

<div>E.g. on the coast of Sweden </div>

<ul> <li>Greater wind speeds during the day (sea breeze) </li> <li>Reversal of wind direction at night - land breeze </li> <li>Circulations are driven by strong surface heating over land - increased air temperatures during the day.</li></ul>

_{EAE2111 2ar}

Question 19

Q

Describe

Sea breeze front

Answer

A

<ul><li>A front is the boundary between two different air masses </li><li>Front boundary between warm land air mass and cool ocean air mass </li><li>Starts initially on the coast, then the zone of uplift moves inland until it may be 50-100 km inland by late afternoon</li><li>At the sea breeze front, warmer land air is lifted over the cooler denser air from the ocean. In turn this uplift can cause condensation and cloud formation. </li><li>Sea breeze can be more than 1 km deep in summer, shallower in winter</li></ul>

_{EAE2111 2as}

Question 20

Q

What is radiation loading?

Answer

A

<ul><li>Differences in net radiation at the surface changes energy balance, hence energy available, at the surface </li><li>K↓ is the largest contributor toward differences in radiation loading </li><li>Angle of incidence (i.e. angle at which the beam hits the surface) dictates the intensity of the radiation via the cosine law of illumination</li>Cosine law of illumination can have significant consequences for global and hemispheric-scale circulations</ul>

_{EAE2111 2at}

Question 21

Q

What are the topography impacts?

Answer

A

<ul> <li>Topography can cause spatial differences in sensible heating (i.e. temperatures), inducing circulations</li> <li>Characteristics of topography make a considerable difference to energy balance, even if the surface properties are the same</li> <li>Often, only difference in the characteristic of land surface is the shape of surface</li></ul>

<div>Note the nonsymmetrical nature of radiation on slopes oriented east or west</div>

_{EAE2111 2au}

Question 22

Q

What are examples of thermal circulations?

At the local and mesoscale

Answer

A

<ul><li>Forest-field circulations </li><li>Field circulations (ploughed-unploughed) </li><li>Urban-rural circulations </li><li>Fire circulations </li><li>Salt lake circulations </li><li>Land-sea circulations</li></ul>

_{EAE2111 2av}

Question 23

Q

What are examples of thermal circulations?

At the synoptic to global scale

Answer

A

<ul><li>Hadley Cell </li><li>Walker Circulation </li><li>Monsoon circulations </li><li>Heat lows and heat troughs</li></ul>

_{EAE2111 2aw}

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EAE2111 - Topic 2 - Wk 2 Flashcards

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