Quiz 3

Question 1

Pressure gradient force (3)

Answer 1

high to low pressure, perp to isobars
large P gradients –> large PGF–> high winds
PGF = (1/rho)(dp/dx)

Question 2

Coriolis force (6)

Answer 2

CF = 2(omega)v sin(phi)
apparent force from rotation of earth
acts perpendicular to wind direction
right in NH, left in SH
proportional to velocity
CF = 0 at equator, max at poles

Question 3

Friction (3)

Answer 3

always opposes wind direction
slows down wind–>reduces CF–>changes wind direction
causes convergence around surface lows, divergence around highs

Question 4

ACF (3)

Answer 4

apparent centrifugal force
acceleration due to change in direction of wind as it moves in circle
always directed outward radially from CoP

Question 5

Geostrophic Wind Balance

Answer 5

wind in absence of curvature and isobars
parallel to isobars
occurs aloft (>1km)

Question 6

Surface winds (no curve)

Answer 6

slows down wind and turns it toward low pressure

Question 7

Winds w curvature (aloft)

Answer 7

air circulates CCW around low, CW around high
for same PGF, gradient wind around a low is slower than geostrophic wind
for same PGF, the gradient wind around a high is faster than geostrophic wind
HOWEVER: pressure gradients are generally greater around low pressure systems, causing higher wind speeds

Question 8

Sea breeze winds (4)

Answer 8

thermal circulation pattern caused by uneven heating of ocean/land
occurs in the day, as land heats faster than water
air rises over land, causing sfc low
sfc high develops over cool ocean

Question 9

land breeze winds (3)

Answer 9

nighttime thermal circulation
land cools fast, causing surface high
relative low develops over ocean

Question 10

Valley breeze (2)

Answer 10

develops along mountain slopes

sunlight warms valley walls, causing air to rise as an upslope wind

Question 11

Mountain breeze (3)

Answer 11

opposite of valley breeze
slopes of mountains cool quickly
cool, dense air glides downhill into valley

Question 12

katabatic winds

Answer 12

strong downsloping mountain breezes caused by the movement of cool, dense air due to gravity

Question 13

Chinook wind

Answer 13

warm, dry wind results from compressional heating of air as it moves down a slope

Question 14

Lake effect

Answer 14

difference in surface friction over lake causes wind direction to change
Over lake: less friction, faster winds, more geostrophic wind

Question 15

Power

Answer 15

energy/time (kw)

Question 16

energy

Answer 16

kwh

Question 17

Wind Power eq

Answer 17

P = 0.5 rho A v^2

total power available in wind

Question 18

rated power

Answer 18

max power a turbine can generate (obtained at rated wind speed)

Question 19

rated wind speed

Answer 19

wind speed that produces the rated power, above rated wind speed, power output is constant

Question 20

cut in wind speed

Answer 20

minimum wind speed for a turbine to begin producing power

Question 21

cut out wind speed

Answer 21

wind speed that turbine shuts off and stops producing power (to prevent damage)

Question 22

turbine efficiency

Answer 22

Nturb = Pturb/Pwind

Question 23

annual capacity factor

Answer 23

CF = 100* Pturb / (Prated * 8760)

Question 24

El nino, La nina: Normal conditions

Answer 24

High pressure over Eastern Pacific = clear skies, cold weather
low pressure over Western Pacific = stormy weather over warm water, high sea level

Question 25

La Nina

Answer 25

Intensified version of normal conditions

high pressure over Peru strengthens, intensifying cycle

Question 26

El Nino

Answer 26

pressure gradient is reversed due to building Siberian high

strengthens equatorial counter current

Question 27

air masses

Answer 27

large bodies of air with similar characteristics

Question 28

C, M, T, P, A, k, w (air masses)

Answer 28

continental, marine, tropical, polar, arctic, unstable, stable

Question 29

Hadley’s Single Cell Model

Answer 29

Proposes a single large circulation cell in each hemisphere
assumptions: no differential heating at surface, sun is directly over the equator, earth doesn’t rotate
not accurate, but good starting point

Question 30

Three cell model

Answer 30

rotation of earth breaks single cell into a series of cells
0deg: intertropical convergence zone
30: subtropical high
60: subpolar low
polar cell, ferrel cell, hadley cell

Question 31

Hadley Cell

Answer 31

warm air rises at ITCZ
moisture condenses, releasing lots of latent heat over equator
aloft, air diverges, moves poleward, and cools
at 30deg, dry air begins sinking and warms w compression (clear skies at 30)

Question 32

Ferrel Cell

Answer 32

a thermally indirect cell: cool air rises, cold air sinks
mild sfc air moves poleward, meeting cold air from poles at 60: (two air masses dont mix b/c of different temps, results in rising air at 60)
winds aloft are westerly

Question 33

Polar cell

Answer 33

surface easterlies result from coriolis force

Question 34

Polar jet

Answer 34

occurs near 60 N/S, moves around a lot though

steering wind for most weather systems int he mid latitudes

Question 35

polar jet mechanisms of formation

Answer 35

increasing N-S pressure gradient at high altitudes (turned westerly by CF)
density decreases with altitude, increases gradient windspeed
sharper temperature gradient at polar front intensifies pressure gradient further
conservation of angular momentum

Question 36

Subtropical jet

Answer 36

occurs at 30deg (W to E flow, relatively zonal)

general mechs of formation are same as polar jet

Question 37

Conservation of angular momentum

Answer 37

angular momentum = mvr
r decreases as latitude increases
in order to conserve momentum, v must increase

Question 38

Wind and ocean currents

Answer 38

wind pulls water along at the surface
because coriolis force deflects water slightly from the wind direction, ocean currents are circular
at lower depths, coriolis turns water further (Ekman spiral, causes upwelling off CA coast)

Question 39

Major currents (7)

Answer 39

peru current, gulf stream, N/S equatorial current, countercurrents, CA current, North atlantic drift, labrador current

Question 40

Major semi-permanent highs/lows (4)

Answer 40

Pacific high, Bermuda high, Aleutian low, Siberian high