Finalized Final Study Guide and Study Questions

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INTRODUCTION TO METEOROLOGY SPRING 2011
FINALIZED FINAL STUDY GUIDE
READ THIS FIRST: this outline is not meant to be fully comprehensive. This lists all the major topics we discussed in class,
but it does not completely cover everything involved with every topic, so use this as a guide to your notes, and to what
to look at in the text.
WHAT THE EXAM WILL COVER: The exam will cover the entire semester’s material. Very approximately, half the exam
will cover new material and half will cover material from earlier in the semester. New material covered by the exam
will include weather patterns (fronts and mid-latitude cyclones), hurricanes, thunderstorms, including lightening and
tornados (read the book!). This is the finalized study guide. Use the study guides for midterms 1, 2 and 3 to review old
material, and use this study guide to review the new material.
WHEN THE EXAM WILL TAKE PLACE: The final will take place at the official, University – scheduled time in your regular
classroom. You can also get a full listing of your final examination times through UVlink. You can also look up the
official times of all finals at www.uvu.edu; from the UVU home page, follow the ‘students’ and ‘class schedules’ links.
INSURANCE: Insurance is not available for the final. This does not mean that you shouldn’t do the recommended
homework.
HANDOUTS: Powerpoint files for the entire semester are available at http://research.uvu.edu/bunds
Outline of what we have covered:
1. Weather Patterns (Fronts!)
a. Basic concept of a front – boundary between two air masses.
b. Warm fronts, cold fronts and occluded front – know these, be able to explain and sketch them
i) long-lasting, relatively gentle precipitation vs. short-lived, strong precip, often with thunderstorms.
c. Dry lines and stationary fronts - know these, be able to explain and sketch them
d. Mid-latitude cyclones
i) Big weather-maker (storms) in the U.S.
ii) Basic description:
(1) Low pressure center
(2) cold air is sucked towards the L from northwest
(3) warm air is sucked towards the L from south
(4) warm front and cold front form (be able to draw a sketch of this like we did in class!!)
iii) More depth to the idea
(1) Cold front catches warm front, forming an occluded front.
(2) Whole system moves roughly west to east with westerlies and polar jet
iv) Formation
(1) Initiate as waves in the polar front and polar jet (see figure 9-10)
(2) Strengthen as they move east
(3) Become occluded, weaken
(4) Also often weaken as they pass over the Rockies, then re-form over the Great Plains
v) More advanced ideas
(1) Upper-air support from divergence aloft
(2) Convergence aloft supports anti-cyclones (High pressure centers)
vi) Local effects and weather that occurs as a frontal system passes.
(1) Warm fronts produce longer duration but milder precipitation, usually.
(2) Cold fronts produce shorter duration but more intense precipitation, usually. Thunderstorms are much more
common with cold fronts than warm fronts due to the much stronger and more rapid lifting of air produced by
cold fronts.
(3) Main example: cold fronts in UT. You should have notes on this regarding warm south wind switches thru
west to northwest, temperature drops, precipitation, etc.
2. Thunderstorms and Tornados (Chapter 11)
a. What is a thunderstorm?
b. Scale (kilometers to tens of kilometers; much smaller than a mid-latitude cyclone).
c. Main types – air mass thunderstorms and potentially severe thunderstorms
d. Air mass thunderstorms
i) Where they occur – often over mountains
ii) Stages of development
(1) Cumulus stage – unstable air rises, forms cumulus cloud(s). Causes of lifting – solar heating, mountains, etc.
(2) Mature stage – intense, large cumulo-nimbus cloud, heavy precip, thunder and lightening
(3) Dissipation stage – large downdrafts dissipate energy and block lifting, storm evaporates
METO 1010, Introduction to Meteorology, Final Study Guide, Prof. Bunds, UVU
page 1 of 4
iii) Usually fairly short-lived – a few hours at most
Severe thunderstorms
i) Larger, more powerful, longer-lived than air mass thunderstorms.
ii) Often form associated with some large-scale phenomenon such as a cold front, dry line, or squall line in front of
a cold front.
(1) Wind shear is usually a key factor
(a) Prevents down drafts from blocking updrafts and destroying the storm
(b) Helps a gust front form in front of downdrafts. Gust front is a mini-cold front that aids lifting in the storm
and can lead to the formation of new storms in front of an existing storm (see fig. 10-6 in your text).
(c) Can lead to formation of a mesocyclone and tornado formation (read about this in your textbook!).
iii) Largest of thunderstorms are call “Supercells” and they are amazing. They can be up to 65,000 feet tall – so
they extend well into the stratosphere! Most large tornados are spawned by supercells.
iv) Squall lines(1) Really, any mesoscale narrow band or line of thunderstorms
(2) Often form in front of a cold front, in the warm, unstable air in front of it (i.e., mT air that has moved from
the Gulf of Mexico over the great plains).
v) Dry line – boundary between cT and mT air over the great plains that can form in the warm sector of a midlatitude cyclone, in advance of the cold front.
f. Lightening
i) First and foremost, charges develop in a cumulonimbus cloud. Negative near the base, positive at the top. This
may happen as part of the formation of hail.
ii) Most lightening is cloud-to-cloud, some is cloud-to-ground (‘ground strikes’).
iii) Strong negative charge in lower cloud induces a positive charge in the air and ground below it. It is possible to
notice this standing on the ground.
iv) Lightening is essentially and electrical connection between the negatively charged lower portion of the cloud
and the ground, so that electrons flow from the cloud to the ground. This is accomplished by a leader and a return
stroke, and is usually followed by 2 to 4 more strokes within a couple tenths of a second. Read about this in your
textbook.
g. Major tornado outbreak weekend of April 14-16.
i) Southeast through Carolinas.
ii) At least 200 reported tornados in 3 days.
iii) Multiple vortex supercells.
iv) Numerous fatalities – many victims were in trailer homes.
v) Major amount of instability, which was well forecasted by the NWS’s Storm Prediction Center (we looked at
soundings & graphs of environmental lapse rate vs adiabatic cooling).
h. Thunder. Caused by lightening, when the current flow in the lightening rapidly and intensely heats the air around
the lightening bolt so that it essentially explodes. The distance between you and lightening can be estimated by the
time it takes the sound to reach you – about 6 seconds per mile at our elevation.
i. Tornados
i) Intense, small-scale wind.
ii) Intense low pressure in the center (up to 10% lower than surrounding air) cause air to spiral inwards and
upwards
iii) Usually visible because low pressure causes air to expand and cool below its dew point. So the tornado is a
cloud. Dust and other material picked up by the wind also makes them visible.
iv) Form in association with severe thunderstorms, especially supercells.
v) Formation – wind shear creates a mesocyclone, which is distorted upwards, stretched, and intensifies. A
tornado can be spawned from the wall of the intense mesocyclon.
vi) Fujita intensity scale (see your text).
Hurricanes (Chapter 12)
a. The most powerful of storms. A single hurricane can spawn many tornados..
b. Called hurricanes in N. American region, cyclones in the Indian Ocean and typhoons in the Western Pacific. All
are the same natural phenomenon.
c. A hurricane is a type of tropical storm with strong low pressure center, strong cyclonic rotation, and very strong
winds. To be classified as a hurricane, a tropical storm must have winds sustained at an average speed of 74 mph for
one minute. That is some strong wind.
d. Conditions for formation:
i) Warm water – over 80oF at the surface (so the tropics)
ii) At least 300 miles from the equator so the coriolis force is strong enough to cause the spinning
iii) Little or no wind shear
iv) Relatively cool air at altitude
e.
3.
METO 1010, Introduction to Meteorology, Final Study Guide, Prof. Bunds, UVU
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v)
Relatively moist air at moderate altitude (15,000 feet) [note that iv and v contribute to unstable atmospheric
conditions)
vi) A trigger, such as powerful thunderstorms and/or a wave in the tradewinds
e. Pressure in the center – can be below 900 mb in the center (wow!)
f. Paths – hurricanes move from east to west with the tradewinds, and curve with the coriolis effect (so to the right in
the N. Hemisphere).
g. Timing – hurricanes can occur from summer to early winter, and are most frequent around the fall equinox.
Study Questions
Do these to help you prepare for the final. You should also be sure to do all the recommended problems from the textbook.
There is no formal insurance for the final, but that should not lessen your motivation to do these questions – in fact it makes
it critical that you do them carefully and completely understand them so that you can do well on the exam.
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What two air masses sometimes collide over the central and SE (southeast) U.S. to produce ‘drylines?’
Draw a side-view sketch of a warm front. Be sure to label the temperature of the air masses and their movement.
What type of weather (and weather changes) would you normally experience as a warm front passes over you in Utah?
Be sure to include temperature, winds and precipitation in your explanation.
Draw a side-view sketch of a cold front. Be sure to label the temperature of the air masses and their movement.
Draw a side-view sketch of a warm front. Be sure to label the temperature of the air masses and their movement.
Draw a side-view sketch of an occluded front. Be sure to include a pine tree and a house in your sketch!
What type of weather would you normally experience as a cold front passes over you? Describe winds, precipitation,
temperature and pressure before, during and after the passage of the cold front.
Sketch a map view of a mid-latitude cyclone, including air pressure, fronts, wind directions and types of air masses
involved.
Draw a series of three sketches that shows the typical evolution of a mid-latitude cyclone, showing the positions of the
warm, cold and occluded fronts that commonly are part of a mid-latitude cyclone.
Why are mid-latitude cyclones important to residents of Utah and the U.S.?
What is the Norwegian model for the formation of mid-latitude cyclones? Explain it, and include how meteorologists
believe waves in the Polar Jet Stream generate mid-latitude cyclones.
How can upper-air flow support or weaken a mid-latitude cyclone?
How are anti-cyclones affected by upper air flow?
What is a thunderstorm?
What are the two main types?
Explain the development and life cycle of an air mass thunderstorm, using three sketches.
Sketch a severe thunderstorm; include regions of warm updrafts and cold downdrafts, gust front, anvil, movement
direction of the storm, and overshooting top.
Severe thunderstorms tend to form in association with mid-latitude cyclones. Explain the 3 main ways this happens,
and why it happens.
What is the name of the most intense of thunderstorms? How tall can they be?
Explain what a mesocyclone is – you’ll need to use a sketch to aid your explanation.
How do mesocyclones lead to the formation of a tornado?
Explain what a gust front is and how it contributes to the development of severe thunderstorms.
What sorts of conditions are favorable for the development of severe thunderstorms (i.e., air mass and atmospheric
conditions).
Explain how lightening forms, in reasonable detail (use your textbook if needed).
Explain what lightening is in one simple sentence.
Is it common for lightening to strike the same place twice? If so, how far apart in time do the strikes usually occur?
(read the book).
How does lightening cause thunder?
How can you potentially determine how far away from you a lightening stroke occurred?
What is the Fujita scale?
In the movie ‘Tornado,’ one of the characters called an F-5 tornado ‘the finger of God.’ Why would someone be
inspired to say that (not from a religious perspective – think in terms of the Fujita scale and the power of an F-5
tornado)?
Can a tornado lift an entire house off the ground?
How wide are tornados, usually?
Describe a hurricane. (where, when, how big, etc.; a sketch will help!).
What other names are used around the world are used to name the storms we call hurricanes? State where each term is
used.
What conditions are favorable for hurricane formation?
METO 1010, Introduction to Meteorology, Final Study Guide, Prof. Bunds, UVU
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What time of year do hurricanes tend to form in the western Atlantic and Gulf of Mexico? Briefly explain why.
For a tropical storm to be categorized as a hurricane, what must the wind speeds be?
Explain what ‘sustained wind’ means, in regards to hurricane winds.
What is the lowest pressure ever recorded in a hurricane?
Is the weather actually calm in the eye of a hurricane?
What 3 main types of hazard do hurricanes pose to people and their property? Explain each hazard.
On which side of a hurricane that strikes the U.S. coast in the Gulf of Mexico would you expect the storm surge to be
strongest (highest)? Draw a simple sketch to illustrate your answer.
43. Why don’t hurricanes form right on the equator?
44. What type of storm commonly affects Utah in the winter, and produces most of our precipitation?
45. What are the major greenhouse gases in the atmosphere?
46. How would Earth’s climate be different if there weren’t a greenhouse effect?
47. Explain the Greenhouse Effect.
48. Explain, using a sketch and words, what a multiple vortex tornado is. Note that we talked about these in class, and you
can find information about them online.
That’s All Folks
METO 1010, Introduction to Meteorology, Final Study Guide, Prof. Bunds, UVU
page 4 of 4
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