ATSC 113 SNOW Exam Questions with
100% Correct Answers (Graded A+)
gradient - Answer-is a change in a property, such as temperature, over a distance
Faceted crystals, or facets, - Answer-are produced when a strong vertical temperature
gradient exists. The water vapour is moving quickly, and crystal growth happens
quickly. The rule of thumb is that faceting takes place when the temperature gradient is
larger than 1°C per 10 cm depth, or equivalently 10°C per metre.
Under these conditions, snow crystals near the bottom of the snowpack (where it is
warmer) can become very large and angular (Fig. 7de.3). This is also known as depth
hoar. - Answer-snow crystals near the bottom of the snowpack (where it is warmer) can
become very large and angular
Rounded crystals, or rounds, - Answer-are produced when temperature gradients are
weak, water vapour moves slowly, and crystal growth happens slowly. Typical rounding
occurs when the vertical temperature gradient within the snowpack is less than 1°C per
10 cm depth, or equivalently, 10°C per metre. - rounding occurs more often in warmer,
wetter, coastal climates, where cloud cover is more frequent, and the snowpack is
deeper
crystal metamorphism - Answer-The characteristics of these little crystals have direct
implications for avalanche danger. Generally speaking, faceted crystals are weakly
bonded, making the snowpack weaker and more unstable. Rounded crystals are
strongly bonded, making the snowpack stronger and more stable.
Deposition - Answer-occurs when a substance undergoes a phase change directly from
the gas to the solid phase, without the liquid stage in between. For instance, the
deposition of water is when it changes from water vapour (gas) into ice (solid) without
passing through the liquid water phase. It literally deposits itself onto the snow surface.
Dewpoint temperature - Answer-is the air temperature at which water vapour starts to
condense into liquid droplets, while being cooled
Frostpoint temperature - Answer-is the dewpoint temperature if the air is below 0°C.
Instead of dew, frost forms.
Surface hoar or hoarfrost or just frost - Answer-is essentially the frozen version of dew.
It is produced by deposition onto the snow surface when the air temperature falls below
the frostpoint temperature. The outcome is the formation of ice crystals on the top of the
snow surface.
, What is needed for surface hoar to form? - Answer-clear night skies, calm winds, A
strong temperature inversion,
temperature inversion - Answer-temperature generally decreases with height in the
troposphere (Fig. 6c.1). However, occasionally temperature can increase with height for
some layer of air in the troposphere
How do inversions occur? - Answer-Subsidence due to high pressure & Radiative
cooling of the ground
On a weather map, what does an isobar represent? - Answer-A line connecting
locations of the same pressure
Complete the blanks in following statements, in order.
_____ kPa is at about sea level elevation /
85.0 kPa is at about ______ m elevation /
______ kPa is at about 3000 m elevation. - Answer-100. / 70.0
The 85.0 kPa level is above which mountain peak? - Answer-Cypress
What is the approximate pressure level at mid-mountain at Lake Louise? (Mid-mountain
is halfway between the elevation of the lake and the mountain top next to the lake.) -
Answer-80.0 kPa
Why is the orientation of the main shaft of a wind barb important? - Answer-It indicates
the direction of the wind
If you see four triangles on a wind barb at the elevation you're planning to ride, what
does this indicate? Assume that the units as are they were presented in the snow
learning goals. - Answer-A good day to stay inside and avoid skiing
How might a weak pressure gradient be represented on a pressure map? - Answer-The
isobars are far apart
What does a temperature contour on a pressure-level map indicate? - Answer-Points
that have the same temperature
What information is necessary in order to interpolate from temperature on a pressure-
level map to a free-air temperature at a different altitude? Select the best answer. -
Answer-ALL OF THE BELOW
The forecasted temperature
Dry or wet adiabatic lapse rate
The forecasted relative humidity
You plan to go skiing with friends at Whistler (elevation ~2000 m), and you have access
to an 85.0-kPa (~1500 m) pressure-level map. The forecasted temperature at Whistler
100% Correct Answers (Graded A+)
gradient - Answer-is a change in a property, such as temperature, over a distance
Faceted crystals, or facets, - Answer-are produced when a strong vertical temperature
gradient exists. The water vapour is moving quickly, and crystal growth happens
quickly. The rule of thumb is that faceting takes place when the temperature gradient is
larger than 1°C per 10 cm depth, or equivalently 10°C per metre.
Under these conditions, snow crystals near the bottom of the snowpack (where it is
warmer) can become very large and angular (Fig. 7de.3). This is also known as depth
hoar. - Answer-snow crystals near the bottom of the snowpack (where it is warmer) can
become very large and angular
Rounded crystals, or rounds, - Answer-are produced when temperature gradients are
weak, water vapour moves slowly, and crystal growth happens slowly. Typical rounding
occurs when the vertical temperature gradient within the snowpack is less than 1°C per
10 cm depth, or equivalently, 10°C per metre. - rounding occurs more often in warmer,
wetter, coastal climates, where cloud cover is more frequent, and the snowpack is
deeper
crystal metamorphism - Answer-The characteristics of these little crystals have direct
implications for avalanche danger. Generally speaking, faceted crystals are weakly
bonded, making the snowpack weaker and more unstable. Rounded crystals are
strongly bonded, making the snowpack stronger and more stable.
Deposition - Answer-occurs when a substance undergoes a phase change directly from
the gas to the solid phase, without the liquid stage in between. For instance, the
deposition of water is when it changes from water vapour (gas) into ice (solid) without
passing through the liquid water phase. It literally deposits itself onto the snow surface.
Dewpoint temperature - Answer-is the air temperature at which water vapour starts to
condense into liquid droplets, while being cooled
Frostpoint temperature - Answer-is the dewpoint temperature if the air is below 0°C.
Instead of dew, frost forms.
Surface hoar or hoarfrost or just frost - Answer-is essentially the frozen version of dew.
It is produced by deposition onto the snow surface when the air temperature falls below
the frostpoint temperature. The outcome is the formation of ice crystals on the top of the
snow surface.
, What is needed for surface hoar to form? - Answer-clear night skies, calm winds, A
strong temperature inversion,
temperature inversion - Answer-temperature generally decreases with height in the
troposphere (Fig. 6c.1). However, occasionally temperature can increase with height for
some layer of air in the troposphere
How do inversions occur? - Answer-Subsidence due to high pressure & Radiative
cooling of the ground
On a weather map, what does an isobar represent? - Answer-A line connecting
locations of the same pressure
Complete the blanks in following statements, in order.
_____ kPa is at about sea level elevation /
85.0 kPa is at about ______ m elevation /
______ kPa is at about 3000 m elevation. - Answer-100. / 70.0
The 85.0 kPa level is above which mountain peak? - Answer-Cypress
What is the approximate pressure level at mid-mountain at Lake Louise? (Mid-mountain
is halfway between the elevation of the lake and the mountain top next to the lake.) -
Answer-80.0 kPa
Why is the orientation of the main shaft of a wind barb important? - Answer-It indicates
the direction of the wind
If you see four triangles on a wind barb at the elevation you're planning to ride, what
does this indicate? Assume that the units as are they were presented in the snow
learning goals. - Answer-A good day to stay inside and avoid skiing
How might a weak pressure gradient be represented on a pressure map? - Answer-The
isobars are far apart
What does a temperature contour on a pressure-level map indicate? - Answer-Points
that have the same temperature
What information is necessary in order to interpolate from temperature on a pressure-
level map to a free-air temperature at a different altitude? Select the best answer. -
Answer-ALL OF THE BELOW
The forecasted temperature
Dry or wet adiabatic lapse rate
The forecasted relative humidity
You plan to go skiing with friends at Whistler (elevation ~2000 m), and you have access
to an 85.0-kPa (~1500 m) pressure-level map. The forecasted temperature at Whistler
