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Salt Lake Community College – Meteorology 1010
Quiz #4
AJ Allred, Adjunct
Student Name: ____________________
1. What latitude zone(s) produce(s) conditions that can erupt into violent frontal/wedge storms?
a. Polar
b. Sub-tropical (‘B’ climate zone only)
c. Tropical
d. Mid-latitude
e. All of the above
Only in the mid-latitudes do we find collisions between large air masses that differ widely in humidity and
temperature. Such collisions provide rapidly rising air that, combined with Coriolis effect, results in
tornadic winds, lightning, hail and heavy precipitation.
2. In a sudden wind shear condition, an airplane pilot may initially react to a microburst by
reducing power after observing an apparent rise in air speed. Reducing power is a good move
because it will help prevent the airplane from overshooting the runway.
True ___
False ___
A pilot entering a micro burst or other downdraft or wind shear will often experience a momentary
headwind that can make the air speed indicator jump to a higher reading and cause additional wing lift. A
pilot may choose to reduce power in order to remain on glideslope. Unfortunately, the next part of the
micro burst or wind shear can produce straight-down or even tail winds, causing a sharp reduction in air
speed, loss of lift and a much lower air speed reading.
3. A ‘lake effect’ condition can occur when air moves over a water body and absorbs moisture.
The fruit country of eastern Michigan and citrus country on the east side of the Black Sea are
good examples.
True ___
False ___
The Salt Lake area can also experience lake-effect storms wherein additional moisture is collected by
wind passing over the Great Salt Lake. The result can be heavier precipitation in Davis County and
further downwind.
4. In the northern hemisphere, Hadley cells produce lush rain forest on the north end and dry or
even desert conditions at the south end.
True ___
False ___
The northern end of a Hadley in the northern hemisphere is the dry end, with descending air (prevailing
high pressure). Climate zone ‘B’ prevails. The south end is the convergence zone, characterized by
wetness, heavy precipitation and tropical climates (A).
5. What air mass condition below is best for inducing a violent frontal storm?
a. 75°F / 50% humidity moving into an area of 80°F /40% humidity
b. 75°F / 50% humidity moving into an area of 65°F /40% humidity
c. 85°F / 50% humidity moving into an area of 80°F /55% humidity
d. 65°F / 40% humidity moving into an area of 95°F /70% humidity
e. 35°F / 40% humidity moving into an area of 45°F /50% humidity
Heat and humidity are important sources of energy for vigorous storms. If there is great contrast in
humidity and heat between two colliding air masses then instability will likely occur. A “dry line” marks
such a boundary, along which rapidly rising air may occur. The best combination of high heat, high
humidity and high contrast between air masses is illustrated in answer ‘d’ above.
6. In a winter weather inversion, which factor is unusually weak or inactive?
a. Morning or valley breeze
b. Canyon or mountain breeze
c. Cold air descending at night
d. Long nights with heavy outbound surface radiation
e. Overcast days and/or clear nights
A morning breeze would help clear out bad air. A canyon breeze or other descending winter air would
just make things colder and heavier and more stable. Night time radiation further cools the already cold
surface. Overcast daytime conditions prevent solar energy from creating warmth and rising air.
7. Typically, an “El Nino” condition means that trade winds pull Pacific ocean water westward less
vigorously or not at all. So, cold water and nutrients are not ‘pulled’ up to the surface along the
coast of South America.
True ___
False ___
Weak trade winds can’t “pull” ocean water westward very usefully, so cold water can’t rise to take its
place along the west coast of the western hemisphere. The concentration of heat and water at the western
end of the Pacific Ocean does is thereby diminished. The normal tropical rains in that areas tend to shift
elsewhere. Utah is one of many places that may then experience unusually heavy precipitation for up to
several months.
8. A “monsoon” condition is mostly about wind. Precipitation may or may not be involved.
True ___
False ___
Monsoon is about wind. If a seasonal wind moves from the ocean to land, it will tend to bring
precipitation after collecting moisture (humidity – latent heat) over the water. If a monsoon wind moves
from land to sea, the atmosphere will tend to be dry.
9. Northern hemisphere ‘jet streams’ result from the Coriolis effect acting on
temperature/pressure differences between polar and equatorial regions.
True ___
False ___
Worldwide, the general prevailing air pressure gradient (from high to low) goes to the north, especially
during winter in the northern hemisphere. That gradient gets pulled or curved to the right by the Coriolis
effect. Thus, winds moving “downhill” to the north tend to get deflected to the right, causing the
westerlies that include high-speed jet streams.
10. High-cost wildfires in coastal Southern California are fed by “Santa Ana” winds caused by low
pressure in the continental interior.
True ___
False ___
The western interior of the United States is generally dominated by high-pressure, descending air masses
produced by Hadley cells. High pressure reaching the surface in Arizona will tend to push outward,
sometimes creating strong winds (like the “Santa Ana”) that can turn Southern California wildfires into
firestorms.
11. Dust devils exhibit the same features as tornadoes, and differ only in size.
True ___
False ___
Dust devils are indeed rising, spinning air; however, they are typically dry, so they will not produce
dangerous winds, hail or lightning. In contrast, a genuine tornado is “re-fueled” by moisture in the storm.
That can provoke much more vigorous conditions than what an ordinary hot day of low pressure can
produce in a dry dust devil.
12. An idealized world model based only on Hadley cells would call for Georgia and Alabama to
have a climate like Arizona.
True ___
False ___
World-wide Hadley cells produce descending air masses that are dry and warming. As such, deserts and
other ‘B’ climates should occur everywhere at about 30 degrees north and south of the Equator. The
southeastern United States is unusual because of trade winds that bring moisture to off-set the dry
conditions that would otherwise prevail.
13. Salt Lake City can experience orographic, convective and frontal precipitation on the same day.
True ___
False ___
Orographic, or ‘mountain’ storms are common in Utah. The presence of water bodies and warm weather
can provoke convective storms, and frontal or wedge conditions can occur any time differing air masses,
such as a cold or a warm front, push through the Utah region. An air masses moving across parts of Utah
can lift by a mountain, then by convection and then participate in a weather front as well.
14. A hurricane will tend to diminish if cloud tops encounter very cold air above them.
True ___
False ___
Bouyant rising air in a tropical storm will eventually cool off or dry out; however, if the top of the storm
encounters very cold air, then any remaining buoyancy will be enhanced by passing through heavier air
around it. Thus, cold air aloft will help extract all possible energy from a tropical storm by helping
preserve buoyancy and continuing lift as high as possible into the atmosphere.
.
15. The passage of a tropical storm will typically exhibit a drop in atmospheric pressure of about:
a. 10mb
b. 35mb
c. 190mb
d. 250mb
e. 500mb
An air pressure change of as little as 35mb is evidence of enough acceleration and spin in rising air to
produce high wind speed and heavy precipitation. Horizontal air pressure changes more than 150mb
would be record-breaking.
16. Cyclonic conditions exhibit all of the following except:
a. Counter-clockwise movement of air
b. Rising air
c. Turbulence, instability, freshening, and/or precipitation
d. Slow descending masses of dry air and/or atmospheric stagnation
e. Collision between very different air masses
High pressure air tends to descend, compressing, warming and turning clockwise as it goes. Such air will
tend to be stable and unlikely to produce precipitation or instability. Cyclonic (counter-clockwise) air
movement is essentially just the opposite in all important aspects.
17. Looking down on a hurricane, which side would probably produce the most storm surge?
a. Right front
b. Left front
c. Right rear
d. Left rear
e. Front and center
The right side wind speed must include the forward speed of the whole storm, plus its own rotational wind
speed. The opposite is true on the left side, where storm winds are reduced by the forward speed of the
storm because they are moving in the opposite direction of the storm. The difference in wind speed that
results from adding or subtracting the forward motion of the storm is enough to make the right side much
more powerful than the left side. In fact, a fast-moving storm can lose so much wind speed on t6he left
side that normal storm surge is sometimes cancelled or even reversed for short periods of time. In
contrast, right side storm surge can be substantially worse than would be produced by high winds in a
stationary storm.
.
18. Many of the most important (and dangerous) weather events are the most difficult to predict.
True ___
False ___
At the human level, micro weather behavior can cause immense havoc yet still be too small for useful prediction.
So, weather forecasts are usually made instead weather predictions, providing a generalized outlook that applies to a
wide area. Sometimes, a microburst or a tornadic twist can be “seen” on radar but even so, such events are so brief
and localized that a genuine prediction, as compared to a forecast, will be out-of-date within minutes. Even an
accurate tornado warning will cause thousands of people to take cover, even though very few of them were in any
actual danger.
19. The magnitude of a tornado is based on the height of the funnel cloud and how long it was on the
ground. Tornadoes that reach the Earth’s surface for more than 1.0 hours typically rank close
to 1.0 on the Enhanced Fujita (EF) scale.
True ___
False ___
Fujita scaling is about apparent effect – bending of metal, shattering of wood, the width of debris path, how much a
brick wall was damaged, and other practical effects. The Fujita scale would be better if there were more measurable
data about wind speed, etc. rather than more about damage reports.
20. What air pollutant is most likely to cause air quality alerts in Salt Lake valley:
a. ozone
b. methane
c. CFC
d. particulates
e. “NOX” and “SOX”
Ozone is produced by solar energy as it reaches oxides of nitrogen and sulfur that are produced mostly by human
activity. Thus, two forms of air pollution help create a third type (Ozone). High Ozone levels are the most
common trigger for issues air quality alerts or warnings in the Salt Lake area.
21. Heavy precipitation in Salt Lake valley this week was caused by:
a. A high-pressure weather front that stalled over the valley
b. A low-pressure weather pattern that stalled over the valley
c. Air-mass thunderstorms that lasted a few minutes
d. A squall line of “dry line” thunderstorms that lasted a few minutes
e. All of the above (downdrafts were accompanied by heavy rain)
22. How does winter differ from summer in Utah?
a. Cyclonic storms predominate in summer, anticyclone storms in winter
b. Low pressure dominates in winter, high pressure in summer
c. Winds prevail from the east in winter, and from the west in summer
d. The Wasatch Front is prone to ‘frontal’ storms that are always snowy
e. None of the above
23. The fact that the most recent “ice age” ended before the rise of significant human populations proves that
climate change is only a natural cycle, not anthropogenic in nature.
True ___
False ___
24. Utah is dominated by “B” and “H” climate zones.
True ___
False ___
25. Places near 30 degrees north or south latitude will tend to be humid, wet and often tropical.
True ___
False ___
26. Surfaces at 30 degrees north or south latitude are likely to receive much more solar energy than do
regions centered near the Equator where the Sun is more often directly overhead.
True ___
False ___
27. A climograph with a steep annual temperature curve is somewhere near the equator or near sea level.
True ___
False ___
28. Water in the atmosphere is the primary cause of ‘sun dogs’, coronas, rainbows and halos.
True ___
False ___
29. Climate change can be detected by which of the following?
a.
b.
c.
d.
e.
Everything below
Sea floor and lake sediments
Tree rings and coal beds
Fossils and wine production
Rocks and ice
30. By how many ppm does current atmospheric CO2 exceed the natural range over 650,000 years?
a. 10
b. 90
c. 900
d. 20
e. 9,000