ATM OCN (Meteorology) 100: WEATHER & CLIMATE

REVIEW QUESTIONS/STUDY GUIDE 
for 3^rd EXAM (5 August 2004)

Summer 2004

TOPICS COVERED FOR THIRD HOUR EXAM

Are you able to answer the following?

• 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 force(s) causes the parcel to move and which forces affect only its directional motion?
• Why is the pressure gradient force divided into two components? 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, 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 on a surface weather map. You should be able to identify the forces involved. What factors influence the strength of the geostrophic wind? How does the geostrophic wind 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 is the actual wind oriented at an angle across the isobars in the friction layers? Compare the frictional effects in each hemisphere. Why does the near-surface 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 differ at different heights?
• Contrast the four scales of atmospheric circulation: planetary, synoptic, mesoscale and microscale. Give examples of each scale.
• What is a thermally direct circulation regime? a thermally indirect circulation regime? Given an example of each regime.
• What is meant by convergence and 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 planetary scale 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 planetary-scale atmospheric circulation change with the seasons?
• What are the two basic factors that determine the general planetary-scale circulation in the atmosphere?
• What are the Hadley cells? How are these cells related to the ITCZ and subtropical highs?
• Relate how the results of the experiment with the dishpan model compare with the atmospheric circulation.
• How is the major poleward transport of heat in the atmosphere accomplished between the equator and about 30 degrees N or 30 degrees S? How is the transport accomplished poleward of 30 degrees N or 30 degrees 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.
• What are the major air masses in terms of the standard meteorological convention? What is required for their formation? Where are the principal source regions found? How are air masses modified as they move from their source region? What are some weather consequences?
• What is a frontal zone? Cold front? Warm front? Stationary front? Occluded front? How do frontal surfaces slope? What criteria are used to locate a front on a surface weather map? Why is a jet stream usually found above frontal zones?
• Clearly understand the features of the Norwegian frontal cyclone model. How does the wind circulate around it? Where does the significant weather (clouds and precipitation) tend to be concentrated? Why? What cloud types are typically associated with a cold front? Warm front? Where would you expect to see such optical phenomena as haloes and corona?
• What is the occlusion process? How does it provide for the conversion of total potential energy to kinetic energy? Describe how the cold and warm fronts move as a low-pressure area develops and moves eastward. How does the wind aloft change as a low forms and eventually occludes?
• With respect to a wave in the westerlies aloft, where do surface lows and highs most often form and intensify? Explain why these locations are favored. Why do most cyclones develop near the jet stream? What geographical regions are favored places for cyclogenesis? Where are the major cyclogenesis regions of North America? How do they vary seasonally? What tracks do these cyclones usually follow?
• Compare the sequence of weather events that occurs when an extratropical cyclone center passes north of you with those that occur when the center passes to the south. Understand veering and backing winds as a low center passes.
• What is zonal flow? meridional flow? What type of weather patterns result from each? What is meant by blocking? What is a cutoff low? What effect does blocking have on the normal sequence of weather events?
• What are the official criteria for a blizzard? Where is the snowfall typically the heaviest with respect to a winter cyclone track?
• What are the various types of anticyclones? Where are some of these commonly found? Identify four potentially hazardous weather situations associations with anticyclones.