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Meteorology Flashcards

(113 cards)

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1
Q

What is the global challenge and why

A

energy security
why:
mitigate global warming
lower air polution

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2
Q

What atmospheric condition does solar depend on (4x)

A

clouds
pollution
haze
T

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3
Q

What atmospheric condition does hydro depend on (2x)

A

precipitations
evaporation (T)

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4
Q

What atmospheric condition does biomass depend on (3x)

A

T
precipitation
growth

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5
Q

What is the Coriolis force?

A

It causes moving objects to be deflected from a straight path due to the rotation of the planet.

Deflection to the right in the Northern Hemisphere

Deflection to the left in the Southern Hemisphere

This is why:

Winds rotate counterclockwise around low-pressure systems in the Northern Hemisphere

Ocean currents and weather patterns are curved

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6
Q

Deflection to the right in the _____ Hemisphere

A

Northern

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7
Q

Deflection to the left in the ______ Hemisphere

A

Southern

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8
Q

Why do air parcels accelerate? What force is it

A

P gradiant (high –> lower)

F = m *a

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9
Q

What is a geostrophic wind?

A

Coriolisforce=Pressuregradientforce

This balance leads to a wind that flows parallel to isobars (lines of equal pressure).

There is no net acceleration, so the wind moves in a steady, straight path.

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10
Q

When are winds strong?

A

when large Pgradiant (dP/dn)

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11
Q

What does the coriolis factor = to at the equator?

A

f = 0

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12
Q

What does cyclonic mean?

A

Low P
Rotation same as earth (counter clockwise)

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13
Q

What does anticyclonic mean?

A

High P
Rotation opposite to earth (clockwise)

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14
Q

Which direction does it rotate when NH, L

A

counter clockwise

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15
Q

Which direction does it rotate when ZH, L

A

Clockwise

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16
Q

Which direction does it rotate when NH, H

A

Clockwise

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17
Q

Which direction does it rotate when ZH, H

A

counter clockwise

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18
Q

What is the Centripetal force?

A

net force that acts on an object moving in a circular path,
–>directed toward the center of the circle.

Keeps the object from flying off in a straight line due to inertia.

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19
Q

Does wind blow faster or slower around a low pressure area at the same gradient?

A

Wind blows faster around a low-pressure area compared to a high-pressure area

due to the added inward (centripetal) acceleration required in low-pressure systems.

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20
Q

Does wind blow faster or slower around a high pressure area at the same gradient?

A

Wind blows slower around a high-pressure area compared to a low-pressure area with the same pressure gradient.

outward curvature means less centripetal force is needed = Coriolis force can be weaker, allowing slower wind speeds

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21
Q

For a low pressure system, where is the COR force pointing

A

outwards

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22
Q

for a high pressure system, where is the COR force pointing?

A

inwards

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23
Q

What is the jet stream?

A

narrow band of very fast-moving air located in the upper atmosphere
from west to east

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24
Q

What causes the jet stream? (2x)

A
  1. T difference: temperature gradient between warm equatorial air and cold polar air.
    = Temperature differences lead to pressure differences
  2. Coriolis force (from Earth’s rotation) deflects it to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. = west - east
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25
If T increases does the P gradient decrease?
NO, it increases
26
As we go up in the atm, the P goes down.
true
27
What is a ridge, what direction?
anticyclonic (clockwise) looser curvatures smaller wind speed
28
What is a trough, what direction?
cyclonic tighter curvatures higher wind speed
29
Where is the speed higher? a Ridge or a Trough?
Wind speed is generally higher near a trough than a ridge in the upper atmosphere.
30
****??? ****How can you tell if there is convergence in a flow on a wind map?
convergence = differential speed = mass flowing to area = ^P in area
31
What are the causes of the spatial pattern of near-surface wind fields?
1. Pressure Gradient Force (PGF) 2. Coriolis 3. Friction 4. Thermal effects 5. Angular momentum
32
What are near-surface wind fields?
within the bottom ~1 km of the atmosphere
33
What are the doldrums?
low wind speed
34
explain the air flow / P at 0°C
warm air --> flows to subtropics --> low P
35
explain the air flow / P at 30°C
flow from tropics and mid-latitude --> high P + air sinks
36
explain the air flow / P at 60°C
flow to subtropics and poles --> low P, air rises
37
explain the air flow / P at 90°C
cold air sinks --> flows from subpolar --> highP
38
Where do we have doldrums/why?
equator no coriolis + weak PGF
39
What is the atmospheric boundary layer (ABL)?
planetary boundary layer (PBL) lowest part of atm that is dirctly affected by surface
40
Explain thermal stability - stable stratification
Return to its original position (stable), no vertical motion
41
Explain thermal stability - unstable stratification
Keep moving away (unstable), motion + mixing
42
Explain the thermal stability concept
how temperature changes with height
43
What happens in unstable conditions?
When an air parcel is lifted, it remains warmer and less dense than the surrounding air at the new altitude. = strong vertical motions and mixing.
44
What is daytime stratification?
thermal layering of the atmosphere near the surface during the day, mainly caused by solar heating of the ground. 1.Sun heats the Earth's surface during the day. 2.The warm ground heats the air immediately above it. 3.This causes the air near the surface to be warmer than the air above. 4.Results in a temperature profile where temperature decreases rapidly with height (steep lapse rate).
45
What is virtual T?
T that dry air would have if P and density = to sample moist air
46
Daytime is stable or unstable stratification?
unstable or neutral
47
Nightime is stable or unstable stratification?
stable
48
What dominates in the inner layer in ABL modeling?
Viscous shear dominates
49
what is ABL
atmospheric boundary layer
50
What dominates in outer layer?
large scale turbulent eddy shear
51
What are assumptions we can make in ABL modeling
1. no Coriolis above ABL 2. no T effects above ABL 3. Turbines in inner layer 4. Outer layer dynamics decoupled
52
What is the logarythmic velocity profile of neutral ABL?
chek
53
what is u* in ABL modeling
friction velocity
54
what is z0 in ABL modeling
surface roughnes lenght
55
what is the value of z0 in open country side?
0.12 m
56
what is the value of z0 in villages
0.3 m
57
what is the value of z0 in water areas
0.001m
58
What is a for flat countryside
0.15
59
What is a for woods
0.25
60
What is a for urban regions
>= 0.3
61
*** ABL unstable inner layer theory
L> 0 = stable L< 0 = unstable
62
What is the solid angle?
important for radiation in 3D unit sphere area radiance
63
What is the zenith angle theta?
between z-axis and angle of emission
64
What is the azimuth angle?
x-axis and line of emission
65
What is the units of incremental solid angle
steradians
66
What is radiance
energy emitted by body / unit area * unit time * unit wavelenght * incremental solid angle
67
What is spectral irradiance?
measure of how much solar power (or radiant energy) is received per unit area, per unit wavelength (or frequency). how solar energy is distributed across the electromagnetic spectrum.
68
What is black body irradiance?
total electromagnetic radiation (power per unit area) emitted by a black body (which absorbs and emits all radiation perfectly at every wavelength)
69
black body irradiance is a function of what
wavelenght T (Planks law)
70
What happens when both sun and earth are considered as black bodies?
analyze the radiative energy balance between them using black body radiation laws. This helps us understand Earth's temperature, energy absorption, and emission.
71
What does the incident solar spectral irradiance at the top of the atm (TOA) orignates from?
Photosphere of the sun
72
Value of emissivity at TOA = ?
1
73
T at TOA = ?
5785K
74
What causes scattering and absorption when looking at the spectral of solar rad?
Atm gases (H2O, CO2) Particles --> aerosol (dust, ff) or hydrometers(clouds, water, rain, snow, hail)
75
What is the ideal balck body T?
520°C
76
in the spectrum of solar rad of earth, what is the yellow?
sunlight without atm absorption
77
Why are there peaks in the spectrum of solar rad of earth
H2O absorbs sunlight = less to earth = ghg
78
why is the red < yellow, where read represents the solar irradiance that reaches the earths surface
because of scattering
79
What is direct radiation?
no scattering from photosphere of sun
80
what is diffuse radiation
scattered from direct solar beam at least once
81
what is reflected radiation?
solar radiation reflected by non-atm object ex: surface
82
% of diffuse radiation of direct flux when no clouds?
10%
83
What is Rayleigh scattering
for PV/gasses most scattering in forward and back directions
84
What is Mie scattering?
particles strong peaks in forwards direction
85
What is isotropic scattering
queal in all directions
86
why is there large diffuse radiation around the sun?
bc of large scattering
87
What are measurments needed for wind ?
Fluctuations "mean wind speed" wind turbine optimal control wind energy ressources power performance structural engineering
88
Name 4 tools for wind measurements.
3 cup aneometer Vane aneometer Sonic aneometer Hot wire aneometer
89
describe 3 cup aneometer
rotation speed is proportional to wind speed
90
describe Vane aneometer
speed and direction
91
describe Sonic aneometer
+ robust ultrasonic sound no moving parts = resist extreme weather lower accuracy --> speed of sound
92
describe Hot wire aneometer
heat loss of electrical heated wire
93
What is ground-based remote sensing in wind?
sound and light wave propagation (ground + satelite) Dopler shift proportional to wind speed
94
Name / explain 2 ground-based remote sensing techs.
LIDAR: light detection raging + wind profiles from space (ressemble à une bouée) SAR: radar/satelite map, orbite on equator
95
Name 4 ways sun radiation can be measured
Pyranometer (global irrad) Sun photometer (direct beam irrad) Pyrheliometer (direct beam irrad) skyscanner (image of sky / effects of clouds)
96
Describe nowcast + timescale
hours current state of atm + extrapolation techniques
97
Describe weather forecast + timescale
days depends on global atm modeling (ATM), -25km
98
Describe seasonal forecast + timescale
seasons *determined by initial state if oceans forces atm = longer predictions if no feedback = little predictibility SLOW
99
Describe decadal forecast + timescale
years GHG + initial state slow + GHG = longer predictibility
100
Describe climate projectipns + timescale
decades statistical info about future weather don't depend on initial state** relies on boundary conditions ( atm comp, ghg, land use)
101
What are the 4 steps of numerical weather prediction cycle?
observe --> analysis --> initialization --> forecast not acurate
102
Name 4 losses of winds tech
repair curtailment turbine and farm interactions transmission/ distribution
103
% of off-shore and on-shore losses
23% onshore 35 % offshore
104
T or F is the reflexion of solar irradiance + important as sun reaches horizon?
true
105
Will the reflexion of solar irradiance increase or decrease w/ lattitude
decrease
106
For PV, what does the optimal tilt angle mean?
greatest anual average inscident solar radiation on pannel
107
is the reflexion of solar irradiance higher or lower in the antarctic?
higher
108
What does the optimal tilt angle depend on?
latitude cloud cover elevation / air polution levels
109
is vertical tracking better thans optimal tilt?
little added value
110
do you want flat or inclined if more clouds for PV?
+ horizontal + clouds = + diffuse = flat angle required
111
PV: what is the ground cover ratio?
pannel collector ares / total ground cover area per panel
112
Do you want flat or tilted PV in the winter
tilted Sun is lower in the sky , A flat panel receives less direct sunlight. now slide off,
113
Do you want flat or tilted PV in the summer?
tilted PV panels — but at a shallower angle compared to winter capture direct sunlight.

Renewable Energy (4 decks)

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