ATSC 113 Final Exam Questions
and Answers All Correct
What do snowcats do? - Answer- Churns, tills, compacts top 10-15cm of snow
increasing snow density & hardness
It is best to let piste harden for ____ - Answer- harden for max time (right after closing).
Hardening is fastest when snow T is closest to 0C
More effective to maintain piste when snow is more dense
How do you harden the piste for racing? - Answer- 1. Snow cats are used to compact
the surface.
2. Man-made snow w/ higher density is used (much smaller & rounded crystals pack
closely).
3. Water may be injected increasing density & hardness. This is best done overnight
during clear sky & cold temp.
4. Mixing salt/fertilizer w/ liq content lowers melting point -> decreases overall
surrounding snow T. After salt-water solution becomes weaker -> melting point
increases and snow refreezes
Katabatic winds - Answer- Downslope movement of air in the absence of large-scale
wind flows. This leads to cold air pooling in the valley.
Cold air pooling may strengthen T inversion
This can last beyond sunrise (takes hrs to dissipate)
Can persist for multiple days
Diurnal slope flow - Answer- Induced by thermal changes as a result of sun heating &
cooling. Most pronounced under high P w/ fair weather.
During radiative heating of day, warm air travels up the Mt side (not vertically) ->
anabatic wind.
As air reaches Mt top, it rises vertically, may form anabatic cumulus w/ enough
moisture.
When sun is strong, as air rises, air descends to replace the space and so on = return
flow. This may dissipate valley fog/ T inversion. *also katabatic winds.
Marine clouds & fog vs Freezing fog - Answer- Marine clouds & fog: move in from
ocean, vertically trapped by a stable layer, some combination of advection & radiation
fog.
Freezing fog: when valley fog forms at T below freezing. Supercooled droplets may form
rime ice.
,Arctic outflow - Answer- Arctic airmass comes from arctic in cold, clear high -P system.
Blows S by Northerly/Northeasterly winds
This cold, dense, shallow air piles up East of Rockies and flows via valleys
Cold fronts that bring arctic airmass from N are arctic fronts
This leads to strong T & P gradients on the Eastern side of Southern coast Mt, P
gradient forces cold air out (gap wind)
Describe Aspect effects - Answer- Southerly aspect = sunny
Northerly = shady
Wet & heavy snow on S & W aspects (wet sluff/slab)
You find crust (refreezing) S & W, but not in N & E
Even when air T above freezing, snow may be below freezing on N aspect -> good
powder (but faceting, surface hoar, persistent weak layer may occur)
During winter, sun hits S-facing slopes more (S > E&W > N)
E & SE get more sun in the morning (coldest) while W & SW get more sun in the
afternoon (warmest)
What are 3 factors affecting wave formation? - Answer- Fetch: distance over water wind
can blow
Duration: amount of time wind blows
Wind velocity
Greater wind velocity-> longer fetch, greater duration-> bigger wave (but if wind speed
slow, waves are small regardless of fetch/duration).
Wave steepness - Answer- Wave height/λ
Confused Sea - Answer- Waves from storm centre may combine w/ others -> large &
small waves of varying λ in dif. direction.
League of Legends Joke 3 - Answer- Q: Why was Caitlyn pulled over on the highway?
A: She was going AD miles per hour.
Wave trains - Answer- waves of different size & velocity dispersing from storm.
Waves move through the group from rear -> front, first gaining in size, shrinking as they
approach the front, then disappearing w/ new waves at the rear (small front & rear, large
mid)
Group velocity - Answer- Velocity at which one group of waves travel
Apparent speed of individual wave is phase velocity (typically twice the group V)
Capillary waves - Answer- Generated by small winds.
Has short λ and surface tension is the restoring force (few cm)
Swell - Answer- Waves that originate from distant sources (storms far away)
Gravity waves that originate from heavy winds capable of travelling far w/ little energy
loss
, Swells w/ longer λ have low height & less susceptible to decay from surface wind
Swell travels shortest distance across Earth's surface
Strong winds on top of swell can create chop/confused sea. Onshore winds(ocean-
>shore) creates chop on incoming swell & reduces wave steepness while offshore wind
slows approaching wave speed smoothing the wave before breaking
Rogue waves - Answer- Occur due to constructive interference carrying high energy but
temporary.
unusually high wave height, rise out of no where, disappears quickly.
Tsunami - Answer- Very long λ waves from seismic events (i.e. earthquakes), λ can be
>200km w/ long wave period, in open ocean they travel fast, but small amp, when near
continental shelf, the wave height increases dramatically.
Swell refraction - Answer- As the swell hits the shallower part the rest of the wave starts
to curve such that wave becomes more parallel to the shoreline.
Swells w/ longer wave periods refract more.
Swell decay - Answer- Process of waves losing energy as they travel from initial
sources. Affected by winds, currents, other waves, etc.
Steeper waves w/ shorter wave periods decay more rapidly
Swells w/ long wave periods and small wave steepness travel w/ little attenuation
When wave steepness is larger than __ , the wave becomes unstable and breaks. -
Answer- 1:7.
As wave drags across ocean floor, λ decreases -> following waves build up behind ->
as λ decreases wave energy is transferred upward -> increased wave height.
What are different types of breakers? - Answer- Spilling: gentle sloping, waves break
long & slow, losing energy as white water spills from the crest
Plunging: moderate-steep bottoms, wave becomes steeper than spilling breakers &
crest falls as a well-defined curl falling fwd w/ a lot of energy
Swinging: long period & low amp wave approaching steep shore, no spill/curl builds up,
slides rapidly up the beach w/ less foam
Tides - Answer- Movement of ocean surface up & down due to g pull of moon & sun
(typically 2 full tide cycles per day)
New moon: moon & sun aligned -> greater pulling -> higher high & lower low tides =
spring tide
Full moon: moon on the opp side of earth from sun
Quarter moon: sun & moon right angle -> opposing forces attenuate each other -> weak
neap tide opp of spring tide
*Tidal range = dif btw highest & lowest tides
Currents - Answer- horizontal movement of water created by rising of tides.
Flood (incoming) & ebb (outgoing)
