REVIEW QUESTIONS/STUDY GUIDE
for 2nd HOUR EXAM (21 November 1997)
ATM OCN 100: WEATHER & CLIMATE

Lecture 3 - Fall 1997

In studying for the exam, review your class notes, the assigned readings in the text including those figures and figure captions emphasized in class and your homework. If you are still not sure, please ask questions before the exam, either during office hours, by appointment or by e-mail.

TOPICS COVERED FOR SECOND HOUR EXAM

WATER VAPOR

• HUMIDITY INSTRUMENTS
  • Sling psychrometers, hair hygrometers, dewpoint hygrometers, hygristors.
• TYPES OF HUMIDITY VARIABLES
  • Vapor pressure, dewpoint, wet-bulb.
  • Apparent temperature/heat stress.
• SATURATION

CLOUDS & FOG

• FORMATION PROCESSES
• CLOUD TYPE CLASSIFICATION SCHEME
• FOG TYPES

PRECIPITATION

• FORMATION THEORIES
• INSTRUMENTS
• PRECIPITATION TYPES
  • ATMOSPHERIC CONDITIONS

ATMOSPHERIC OPTICS

• SCATTERING PHENOMENA (Rayleigh & Mie)
• REFRACTION PHENOMENA - Mirages
• OPTICAL PHENOMENA ASSOCIATED WITH LIQUID WATER DROPS
  • RAINBOWS
  • CORONAS & GLORIES
• OPTICAL PHENOMENA ASSOCIATED WITH ICE CRYSTALS
  • HALOES & SUNDOGS

WINDS & WIND THEORY

• WIND MEASUREMENTS & INSTRUMENTS
• EQUATION OF ATMOSPHERIC MOTION
  • COMPONENTS
• SIMPLE MODELS: Hydrostatic, Geostrophic, Gradient, Friction Layer
• LINKAGE BETWEEN VERTICAL & HORIZONTAL FLOW
  • EQUATION OF MASS CONTINUITY
  • DINES' COMPENSATION
• LOCAL ATMOSPHERIC CIRCULATION REGIMES
  • LAKE (SEA) - LAND BREEZE
  • MOUNTAIN - VALLEY BREEZE
• UPPER AIR OBSERVATIONS & DISPLAY
  • OBSERVATIONS, INSTRUMENTS & PLATFORMS
  • UPPER AIR CHARTS

PLANETARY SCALE ATMOSPHERIC CIRCULATION REGIME

• Prevailing Winds & Semi-permanent Pressure Systems
• Relating the Planetary-Scale Atmospheric Circulation Regime to:
  • Large-Scale Oceanic Circulation Regime
  • Biomes
• Anomalous Circulation Patterns
  • El Niño and Southern Oscillation
  • La Niña
• Monsoon Circulation Regime
• Theories & Models Explaining Planetary Scale Circulation
• Jet Streams
• Thermal Wind

Are you able to answer the following?

• What is atmospheric humidity, and how is it measured? What are typical parameters of atmospheric humidity? Give representative values for each.
• Define vapor pressure and saturation vapor pressure; mixing ratio and saturation mixing ratio, relative humidity, dewpoint and wet bulb temperature. Why is the dewpoint the best indicator of the actual vapor content of the actual atmosphere? Why does the relative humidity undergo a diurnal variation, usually being higher at night than in mid-day, even though dewpoint may exhibit little change?
• What is apparent temperature (heat index) and why is it significant? What factors are needed to determine the apparent temperature? Given these factors, determine the apparent temperature from the provided table. What do your answers indicate about human comfort?
• Given an air parcel, what are the two ways needed to achieve saturation? What is meant by saturation? What is supersaturation?
• What is a saturation adiabatic process? What are the dry adiabatic and saturation adiabatic lapse rates and how are these process lapse rates used? Why does a difference exist between these two process lapse rates? Clearly understand the difference between the process lapse rates and the actual or environmental lapse rate. This distinction is fundamental!
• What is the LCL? What happens when air moves over mountain ranges? What is a chinook, (or a foehn) and a Santa Ana?
• What are the three basic ingredients needed for cloud formation? Understand the mechanisms needed for the formation of clouds.
• What is fog? How does fog compare with clouds? What are the various fog types? How are these fogs formed? How are dew and frost typically formed?
• In what ways do the cumuliform and stratiform cloud formation mechanisms differ?
• What are the various cloud types? Can you name the 10 major cloud genera? What are some identifying characteristics of each, to include optical features (corona, halo)? Which clouds are considered warm clouds, with liquid water droplets? Which are cold clouds with ice crystals? Which clouds typically produce the most precipitation?
• Given a cloud, what additional "ingredients" are usually necessary for precipitation formation, particularly in middle and higher latitudes? What factors hinder precipitation formation?
• Can you identify the three precipitation formation theories? What is the basic premise of each? Why is the simple diffusion-condensation process inefficient? What process or processes are important for explaining precipitation in tropical and in extratropical latitudes?
• What is meant by freezing nuclei? What is the difference between condensation and freezing nuclei? What is the difference between "warm" rain and "cold" rain? How does each of these precipitation types form?
• How is precipitation measured? What are the precautions used in measurement of precipitation?
• Can you distinguish between the types of precipitation? What are the atmospheric conditions associated with each precipitation type?
• What is done in attempts to stimulate artificially precipitation (two ways)? What atmospheric conditions are needed to stimulate significant precipitation?
• Do you know the differences between scattering, reflection, refraction, dispersion and diffraction?
• Why is the sky blue, the clouds white and sunsets red?
• What produces a rainbow? Where in the sky do you usually see rainbows? How are they formed? What are the color sequences of the primary and secondary rainbows? What meteorological significance is associated with rainbows?
• Distinguish between a halo and a corona. What cloud type(s) would produce these phenomena? When and in what direction would you look for coronae and haloes? What meteorological significance is associated with these individual optical phenomena?
• What is a glory? What produces a glory? In what direction would you expect to find a glory?
• What is a mirage? How is it formed?
• Do you know the difference between a vector and scalar quantity? Can you describe speed, velocity, acceleration, and force? Can you provide vector representations? Relate these vector quantities to Newton's Laws.
• What do Newton's Laws of Motion say (the first and second laws)?
• What is the equation of atmospheric motion? Thoroughly understand what the atmospheric equation of motion states.
• What are the forces that can cause an air parcel to accelerate? In which direction does each force act? Which forces cause the parcel to move and which affect only its directional motion?
• Into what two components is the pressure gradient force divided? Contrast the relative size of the horizontal pressure gradient force with the vertical pressure gradient force.
• What does hydrostatic equilibrium mean? Which two forces are involved in this relationship? If hydrostatic balance exists (and continues to exist) will air that is rising continue to rise, stop rising, sink? Why?
• Know how to draw the horizontal pressure gradient force on surface weather maps analyzed at sea level with isobars, identifying the direction of this force and its relative magnitude.
• Understand the Coriolis effect. Why is it caused, what is its direction and what are the three factors affecting the magnitude of this effect?
• What is the geostrophic wind? What assumptions are made to obtain the geostrophic wind? What are the consequences of these assumptions? Name some situations where these assumptions are poor. Be sure you can draw the geostrophic wind vector for both hemispheres from a given pressure pattern. You should be able to identify the forces involved. What factors influence the strength of the geostrophic wind? How does it vary with latitude for the same horizontal pressure gradient?
• How does the geostrophic wind blow in the Southern Hemisphere as compared to the Northern Hemisphere?
• Why does the wind blow across the isobars in the friction layers? Compare the frictional effects in each hemisphere. Why does the wind often die at sunset? (The atmosphere becomes more stable and the influence of friction is concentrated in a shallower layer of air than during mid day.)
• What is the orientation of the winds around a cyclone? an anticyclone? How does friction affect these flow patterns?
• What force relationship exists for the maintenance of the gradient wind around a cyclone? Around an anticyclone? Be able to draw all the force vectors responsible for gradient wind flow. Contrast the gradient wind flow around Northern Hemisphere cyclones and anticyclones with that around Southern Hemisphere cyclones and anticyclones.
• Above the friction layer, what causes the wind speed and direction to be different at different heights?
• Contrast the three scales of atmospheric circulation: general (or primary), secondary and tertiary. Give examples of each scale.
• What is a thermally direct circulation regime? a thermally indirect circulation regime? Given an example of each.
• What is meant by confluence, difluence, speed convergence, speed divergence?
• What is Dines Compensation and what are its implications? What conditions must occur for a surface low to deepen? To weaken? How do surface highs strengthen or weaken?
• Do you understand how differences in heating (or cooling) are needed to initiate air motion? In other words, what are the two ways in which horizontal pressure gradient forces develop? Which mechanism is most fundamental?
• Can you explain how the sea (or lake) breeze develops? The land breeze? Why does water heat and cool more slowly than land? (List 4 reasons) Why does the sea breeze tend to blow parallel to the coastline near the onset of early evening?
• Locate and describe the major prevailing wind and/or semi-permanent pressure systems of the general circulation (e.g., polar easterlies, westerlies, etc.). Which two systems are responsible for producing the major precipitation pattern of the earth?
• How do the major wind systems (belts) of the general atmospheric circulation change with the seasons?
• What are the basic factors that determine the general planetary scale circulation?
• What are the Hadley cells? How are these cells related to the ITCZ and subtropical highs?
• Distinguish between the Hadley and Rossby regimes. What is the likely cause of the difference?
• How is the major poleward transport of heat in the atmosphere accomplished between the equator and about 30°N or 30°S? How is the transport accomplished poleward of 30°N or 30°S?
• In the middle latitudes why does the wind become more westerly and stronger aloft (above the friction layer)? How is the thermal wind defined? What is the relationship between the thermal wind and mean isotherms (for a layer) in the Northern Hemisphere? Southern Hemisphere?
• At what height is the wind speed in the jet stream normally the strongest? Why does the wind tend to be strongest at this altitude and then weaken farther aloft?
• Why is the jet stream strongest above Japan? In which season is this so?
• What is the circumpolar vortex? Why does it exist? In what season is it strongest and largest? Why? What factors cause waves to form in the westerlies? What are Rossby waves? What role do these waves play in energy transport?
• Why do cyclones and anticyclones in middle latitudes generally move from west to east? Why do they generally move eastward more rapidly in winter than in summer? Are you sure that you know the basic cause?
• Where are the major wind driven ocean currents? What is upwelling? Where and why does it occur? What is El Niño? Southern Oscillation? What is La Niña?
• What are the monsoons? What causes them? What effect do they have on the climate of various regions? Compare and contrast the monsoon circulation with land-sea breeze regimes.

Last revision 11 November 1997