Download MET 101: Exam 2 Study Guide

MET 101: Exam 2 Study Guide
Chapter 4: MOISTURE AND ATMOSPHERIC STABILITY
Learning Objectives: You should be able to:
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Describe the movement of water through the hydrologic cycle.
Summarize the processes by which water changes from one state to another, and know what happens to
latent heat during each change.
Distinguish among absolute humidity, mixing ratio, vapor pressure, relative humidity, dew point
temperature, and saturation vapor pressure. Also, know which of these variables are temperaturedependent and state the relationship between temperature and each of them.
Identify the two ways in which relative humidity can be changed and list three major ways in which air
temperatures change in nature.
Understand the importance of dew point temperature and how it is different from relative humidity.
Describe two methods of measuring relative humidity.
Describe adiabatic temperature changes and differentiate between the dry adiabatic rate and the wet
adiabatic rate.
Describe the four mechanisms that cause air to rise.
Define the environmental lapse rate and understand how it determines the stability of air.
Define the three fundamental conditions of the atmosphere and recognize weather conditions associated
with stable and unstable air.
List and describe the factors that modify the stability of air.
Define the terms listed in the vocabulary review.
Chapter 4 Outline:
I.
Movement of Water through the Atmosphere
A. Hydrologic Cycle
1. Evaporation
2. Precipitation
3. Runoff
4. Infiltration
5. Transpiration
6. Water balance
II. Water’s Changes of State
A. Ice, Liquid, Vapor
B. Latent Heat
1. Melting
2. Freezing
3. Evaporation
4. Condensation
5. Sublimation
6. Deposition
III. Humidity: Water Vapor in the Air
A. Measuring actually amount of water vapor in the air
1. Absolute Humidity
a. Mass of water vapor in a given volume of air (density)
b. Affected by changes in pressure and temperature which change its volume
c. Not easily measured
2. Mixing Ratio
a. Mass of water vapor in a mass of dry air
b. Not affected by changes in pressure and temperature
Exam 2 Study Outline
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c. Preferred by meteorologists
d. Like absolute humidity, mixing ratio is not easily measured.
B. Vapor Pressure and Saturation
1. Saturation vapor pressure
C. Relative Humidity - An indicator of how close the air is to being saturated
1. How relative humidity changes
a. Adding or subtracting moisture
b. Relative humidity changes with temperature
c. Natural changes in relative humidity
D. Dew point temperature
IV. Humidity Measurement
A. Hygrometers
B. Psychrometer
V. Adiabatic Temperature Changes
A. Dry Adiabatic Rate
B. Wet Adiabatic Rate
C. Lifting Condensation Level
VI. Processes that Lift Air
A. Orographic Lifting
1. Rain shadow desert
B. Frontal Wedging
C. Convergence
D. Localized Convective Lifting
VII. Atmospheric Stability
A. Absolute Stability
B. Absolute Instability
C. Conditional Instability
VIII. Stability and Daily Weather
A. How Stability Changes
B. Temperature Changes and Stability
1. Radiation cooling from clouds
C. Vertical Air Movement and Stability
1. Subsidence
Chapter 5: FORMS OF CONDENSATION AND PRECIPITATION
Learning Objectives: You should be able to do the following:
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Discuss the role of condensation nuclei in the formation of clouds.
Discuss the basis for the classification of clouds.
Identify major cloud types on the basis of their form and height.
List five types of fog and discuss the details of their formation.
Understand how and why dew and white frost form.
Outline the steps in the formation of precipitation according to the Bergeron process, and describe the
formation of precipitation according to the collision–coalescence process.
Distinguish among rain, snow, sleet, glaze, and hail and describe the circumstances under which each of
them forms.
Discuss the factors that are necessary to obtain an accurate measurement of rain and snow.
Discuss the three categories that intentional weather modification falls into.
Identify some applications that employ intentional weather modification using modern weather
technology; for example, cloud seeding, and so on.
Define the terms listed in the vocabulary review
Exam 2 Study Outline
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Chapter5Outline
I. Cloud Formation
A. Condensation
1. Condensation nuclei
B. Growth of Cloud Droplets
II. Cloud Classification
A. Form
1. Cirrus
2. Cumulus
3. Stratus
B. Height
1. High clouds
a. Cirrus
b. Cirrostratus
c. Cirrocumulus
2. Middle clouds
a. Altocumulus
b. Altostratus
3. Low clouds
a. Stratus
b. Stratocumulus
c. Nimbostratus
4. Clouds of vertical development
a. Cumulus
b. Cumulonimbus
5. Other cloud descriptions
a. Uncinus: Hooked-shaped
b. Fractus: Broken clouds
c. Mammatus - Rounded bottom surfaces resembling utters of cows
d. Lenticular: Lens-shaped clouds
III. Types of Fog
A. Fogs Formed by Cooling
1. Radiation fog
2. Advection fog
3. Upslope fog
B. Fogs Formed by Evaporation
1. Steam fog
C. Frontal or precipitation fog
IV. Dew and Frost
V. How Precipitation Forms
A. Precipitation from Cold Clouds
1. The Bergeron process
a. Supercooled
water
b. Freezing nuclei
B. Precipitation from Warm Clouds
1. The collision-coalescence process
VI. Forms of Precipitation
A. Rain
1. Drizzle
2. Mist
B. Snow
1. Snow flurries
Exam 2 Study Outline
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2. Blowing snow
3. Drifting snow
4. Blizzard
5. Severe blizzard
6. Heavy snow warning
C. Sleet and Glaze (freezing rain)
D. Hail
E. Rime
VII. Precipitation Measurement
A. Standard Instruments to Measure Rainfall
1. Standard rain gauge
2. Tipping-bucket gauge
3. Weighing gauge
B. Measuring Snowfall
C. Measurement Errors
D. Precipitation Measurements by Weather Radar
VIII. Intentional Weather Modification
A. Cloud Seeding
B. Fog and Cloud Dispersal
C. Hail Suppression
D. Frost Prevention
IX. Understanding the Role of Clouds in the Climate System
Chapter 6: AIR PRESSURE AND WINDS
Learning Objectives: You should be able to do the following:
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Define air pressure and the units of force used to measure it.
Discuss how a mercury barometer and an aneroid barometer measure air pressure.
State and understand the ideal gas law.
Describe the “normal” decrease in pressure experienced with increased altitude using the standard
atmosphere.
List the three factors that control wind and briefly describe each.
Write a generalization relating the spacing of isobars to the speed of wind.
Describe the relationship between hydrostatic equilibrium and gravity.
Explain what geostrophic winds are and describe their behavior.
Define gradient winds.
Discuss cyclones and associated cyclonic flow as well as anticyclones and associated anticyclonic flow.
Discuss what troughs and ridges are.
Sketch a diagram (isobars and wind arrows) showing the winds associated with centers of high-pressure
and low-pressure in both the Northern and the Southern Hemispheres.
Describe airflow associated with cyclones at the surface and aloft.
Describe airflow associated with anticyclones at the surface and aloft.
Discuss the relationship between pressure tendency and forthcoming weather.
List instruments used to measure wind speed and wind direction.
Define the terms listed in the vocabulary review
Chapter6Outline
I. Understanding Air Pressure
A. Caused by weight of air
B. Differences in air pressure result from the uneven heating of Earth's surface .
Exam 2 Study Outline
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II. Measuring Air Pressure
A. Mercury Barometer
1. Inches of mercury
a. Not a true unit of pressure, but is an indicator of high or low pressure.
b. Millibar (mb) - The standard unit of true pressure used on weather maps.
B. Aneroid Barometer
C. Barograph 1. Recording aneroid barometer
2. Barogram - paper record produced by the barograph
III. Pressure Changes with Altitude
IV. Horizontal Variations in Air Pressure
A. Influence of Temperature and Water Vapor
1. High pressure
2. Low pressure
B. Airflow and Pressure
1. Convergence
2. Divergence
V. Factors Affecting Wind
A. Pressure-gradient Force
1. Isobars
2. Pressure gradient
a. Horizontal
b. Vertical
1. Hydrostatic equilibrium
B. Coriolis Force
C. Friction
VI. Winds Aloft and Geostrophic Flow
A. Geostrophic Winds
B. Buys Ballott’s Law
1. In the Northern Hemisphere, with your back to the wind
a. Low pressure is on your left.
b. High pressure is on your right.
2. In the Southern Hemisphere
a. Low pressure is on your right.
b. High pressure is on your left.
VII. Curved Flow and the Gradient Wind
A. Gradient Winds
B. Cyclonic Flow
1. Convergent
2. Counterclockwise (N. Hemisphere)
C. Anticyclonic Flow
1. Divergent
2. Clockwise (N. Hemisphere)
D. Upper Air Flow
1. Troughs - Associated with surface lows
2. Ridges - Associated with surface highs
VIII. Surface Winds
A. Convergence
B. Divergence
IX. How Winds Generate Vertical Air Motion
A. Vertical Airflow Associated with Cyclones and Anticyclones
1. Pressure tendency or barometric tendency
B. Factors that Promote Vertical Airflow
Exam 2 Study Outline
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X. Wind Measurement
A. Wind Vane
B. Prevailing Wind
1. Wind rose
C. Cup Anemometer
D. Aerovane
Exam format:
Part 1 will be comprised of 44 multiple choice questions.
Part 2 questions are constructed response. Be prepared to discuss the following items.
1. Weather Maps
a. Interpreting a surface map with station models and isobars: Be able to:
i. Interpret air pressure by reading station model data and identifying the
location of high and low pressure centers base on isobars;
ii. Describe the wind patterns associated with surface low pressure centers and
high pressure centers.
iii. Infer high or low relative humidity based upon the air temperature and
dewpoint temperature plotted on a station model.
iv. Read the wind direction plotted on a station model.
b. Upper Level Map (500 mb):
i. Based on the isolines that show the altitude at which the air pressure is 500
millibars:
1. Identify the location of an upper level trough.
2. Identify the location of an upper level ridge.
ii. Identify the surface weather conditions associated with upper level troughs
and ridges.
2. Weather Instruments
a. Be able to identify various weather instruments and what weather variables they
measure.
b. Know how each weather instrument works.
3. Be able describe why a parcel of air expands as rises.
4. Compare the actual water vapor content of saturated warm are to saturated cold air.
5. Humidity:
a. Describe the difference between absolute humidity and mixing ratio.
b. Understand why meteorologists prefer to use mixing ratio to describe the actual
amount of water vapor in the air.
c. Describe how the temperatures shown on a sling psychrometer vary when the
relative humidity is low compare to when it's more humid.
6. Be able to calculate the amount of latent heat gained or lost when water changes phase.
(Equations and latent heat values will be given.)
Exam 2 Study Outline
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