Homework Questions #3: Answeres
1. A surface ____low_____ pressure system is a cyclone and a surface ____high________
pressure system is an anticyclone. (see note packet 2, V A and B, p. 13)
2. Winds flow ______counterclockwise______ around a cyclone and _____clockwise______
around an anticyclone in the Northern Hemisphere. (see note packet 2, V A and B, p. 13)
3. Extreme extratropical cyclones (ECs) will develop along and follow the ___jet stream____
in midlatitudes during the ______cold/cool_____ season(s) which is where and when the
_____temperature________ contrast in the atmosphere is the strongest.
4. Blizzards and ice storms (extreme ECs) are most common along the ___East___ Coast
of ____North America_____ .
5. Why are blizzards and ice storms most common in this region?
Due to the clash of very cold arctic air with very warm ocean currents as well as the
orientation of the curvature of the jet stream in this region.
6. Fronts are boundaries between air of different density. The boundary between cold air to
the north and warm air to the south in midlatitudes along which the jet stream and ECs
form is called the ____polar____ front.
7. As an EC develops, the counterclockwise circulation around the surface low generates
smaller-scale fronts, mainly _____cold______ fronts extending to the west of the low and
____warm_____ fronts extending to the east of the low.
8. A cold front is represented on a surface weather map as a __blue line with triangles__ and
a warm front is represented as a ______red line with semi-circles________.
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9. Cold front’s have a ____steep_____ slope which causes the precipitation to fall in a
_______narrow_______ band.
10. Precipitation caused by a cold front is most frequently in the form of ___rain_____.
11. Why is the preciptiation assocciated with a cold front usually in this form?
Because the precipitation is occurring in the warm air being lifted by the front.
12. Compared to cold fronts, warm fronts have a __more gradual__ slope and they move at
a ____slower____ speed which is why the precipitation associated with a warm front
tends to cover a ____larger____ area and be of lighter intensity than a cold front.
13. With a winter EC, as one moves from north to south relative to a warm front the
precipitation transitions from ______snow______ to ______sleet_______
to _____freezing rain_______ to _____rain________.
14. Occluded fronts develop late in the EC life cycle when the faster moving __cold front___
catches up to the ___warm front_____.
15. Dry lines act like cold fronts and lift air as they move east because ___dry___ air is
heavier than ___moist___ air.
16. What type of extreme weather is associated with dry lines?
Severe thunderstorms
17. Where are dry lines most common?
Tornado alley (southern U.S. Great Plains)
18. In a blizzard heavy snow combines with ___strong winds___ to create reduced visibility.
____Cold_____ is the other common dangerous blizzard component.
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19. An East Coast blizzard is usually associated with an ____amplified____ jet stream wave
pattern.
20. Strong divergence at the tropopause results because this type of jet stream wave pattern
because it is associated with what two jet stream features?
Jet streaks and curvature
21. A _____double_____ jet streak configuration, which results is superimposition of
multiple (three) divergence areas is frequently present.
22. Why does a blizzard have such strong winds?
Due to deep surface low pressure and, thus, a strong pressure gradient.
23. Why does an EC located just off the East Coast and in the upper Great Plains (U.S.)
have stronger winds than similar ECs in other locations?
Ocean surface and flat, featureless surface of Great Plains have less friction to slow down
the wind.
24. Blizzard conditions occur just to the ____north and northwest____ of the track of the
surface low pressure system (storm track).
25. _____Orographic________ lifting results in mountain and upslope blizzards in the
western U.S.
26. The main cause of lake-effect blizzards is that the lake water (at the surface) is much
warmer that the atmosphere aloft (steep environmental lapse rate), resulting in
accelerated upward motion. This is called ______environmental instability______.
27. Heavy snow combines with ____strong winds_____ to cause power outages during a
blizzard.
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28. Can coastal flooding be a significant impact of a blizzard along the East Coast?
Yes
29. Why is an East Coast blizzard likely to have a greater impact in the southern states that
are affected, even if there is a greater snowfall accumulation to the north? (see impacts
during superstorm, IV C, on p. 10)
1. Because heavy snow is rare, they are usually more unprepared
2. The snow usually has a heavier weight, due to higher water content (warmer
temperatures), so that it can result in more damage
30. Which of the following is not a common cause of blizzard fatalities: hypothermia
(freezing to death), traffic accidents, heart attacks during snow removal, suffocation in
a giant snow pile, drowning at sea?
Suffocation in a giant snow pile
31. Name three positive blizzard impacts.
1. Water supply – snowmelt runoff
2. Societal – can bring together community
3. Psychological – bright due to reflection of light
4. Aesthetic – beauty of snow
5. Human health – snow sports
6. Economic - tourism
32. A large outbreak of _____thunderstorms______ over the Gulf of Mexico caused
a massive release of _____latent heat____ into the atmosphere that resulted in rapid
development of the 1993 “Superstorm” in its early stages along the Gulf Coast.
33. ______Freezing rain_______ is the type of precipitation that occurs during ice storms.
34. This type of precipitation occurs in situations where a layer of _____warm air_______
overrides a thin layer of ______cold air_______ near earth’s surface.
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35. Ice storms occur just to the north of ____warm____ and ____stationary______ fronts.
36. The critical atmospheric feature in causing an ice storm is ___a cold arctic anticyclone
____(surface high pressure system) to the north____ which provides a continual supply of
cold air near the surface.
37. In contrast to blizzards, the ECs associated with ice storms are much ____weaker____.
As a result, the winds during ice storms are ____much lighter_____.
38. The main impact of ice storms are ______power outages_______which are caused by the
_____shear weight _____ of the ice on power lines and trees.
39. What about the geographical location of Montreal resulted in it being so hard hit by the
1998 ice storm?
It is located in the St. Lawrence river valley which is oriented so that northeasterly wind
from the cold anticyclone could drive cold, dense low level air down the valley where it
was trapped.
40. What about the weather for the weeks following the storm worsened the impact?
Temperatures were extremely cold and many homes had no heat due to widespread
power outages.
41. The north-south (meridional) temperature contrast will (has) ___weakened____ with
global warming. This will tend to ____weaken____ the jet stream which should result
in a ___decrease____ in the frequency and intensity of Extreme ECs.
42. In what manner has the EC storm track shifted, and is likely to continue to shift with
further global warming, over the past several decades?
Shifted poleward
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