Geography 1
Exam 2 Study Guide
Physical Geography
Chapter 4: Atmospheric Moisture and Precipitation
Review the following concepts from this chapter:
Adiabatic cooling
Adiabatic heating
Stability
Instability
Environmental lapse rate
Types of lifting: convectional, convergent, frontal, orographic
Chapter 5: Global Atmospheric and Oceanic Circulation
1. Measuring atmospheric pressure: millibars, barometer, mercury, lbs/square inch
2. Inverse relationship between elevation and pressure
3. Wind a function of pressure difference; greater the gradient, stronger the wind
4. Wind direction and speed determined by: pressure gradient, Coriolis effect, friction
5. Why variability in pressure? Could be due to variability in heating (land vs water for instance)
6. Isobars
7. Coriolis effect: to the ‘right’ in the northern hemisphere; to the ‘left’ in the southern hemisphere
8. Geostrophic winds: upper atmosphere, only pressure gradient and Coriolis effect matter, wind
flows parallel to isobars
9. Surface winds: wind moves out of high pressure across the isobars due to friction
10. Anticyclone: high pressure, wind diverging and sinking and heating, clockwise (northern
hemisphere)
11. Cyclone: low pressure, wind converging and rising and cooling, counter-clockwise (northern
hemisphere)
12. Ideal model of global winds and pressure (without land masses and without seasonal
variability)
13. Tropics: equatorial low as convectional lifting causes warm air to rise and cool, condensing
and precipitating. Very light winds, ITCZ. Migrates seasonally. Is pulled especially far north in the
northern hemisphere summer (June, July, August…)
14. Hadley cell: the rising air from the equator sinks at 30 degrees, heats adiabatically as it sinks
and becomes very dry, creating the STH (subtropical high). It also migrates seasonally. In the
northern hemisphere in summer it becomes fixed over the oceans—Hawaiian High and Azores
High. The Hawaiian High with its clockwise rotation pushes moist air masses away from California
and coastal North America. The Azores High with its clockwise direction pushes warm moist air
masses towards the southeastern U.S.
15. Midlatitudes: prevailing winds are the westerlies, creating an eastward flow of air (northern
hemisphere). These collide with the cooler air masses being pushed out of the polar high pressure
area and frontal lifting occurs, creating the polar front (subpolar low pressure). It is low pressure
because air masses are being lifted (always the warmer air masses) and midlatitude cyclones are
forming.
16. Jet stream: geostrophic wind that influences midlatitude cyclones. When the jet stream is
moving from a ridge to a trough formation, there is divergence at the surface which prevents
storms from forming; when the jet stream is moving from a trough to ridge formation, there is
convergence at the surface, increasing the storm formation
17. Seasonal variability: the subtropical high remains over oceans in the summer months because
the land has heated up and has lower pressure. The reverse is true in winter—the land masses
have cooled, creating high pressure and the subpolar low forms over the oceans (Aleutian Low and
Icelandic low). Each of these subpolar lows brings cyclonic storms to the continents (to North
America and to Europe).
18. Local winds are influenced by the daily change in temperature; during the day it is warm inland
and low pressure is created so a sea breeze is experienced with winds coming from the sea toward
the land. In the evening and and night the land cools and creates high pressure, so the wind
moves from land to sea, creating a land breeze.
19. Santa Anas are a local wind influenced by marked changes in temperature (and therefore
pressure) between land and ocean in the late fall and winter. As the interior cools (Great Basin),
high pressure begins to form. The warmer (relatively) oceans have lower pressure and air is pulled
from the Great Basin towards the coast, over Southern California.
20. Ocean currents: these mirror the global wind systems and generally move warm waters
poleward and cool waters equatorward. A gyre is a large circular ocean movement.
21. El Nino: the usual pattern of moving warm waters away from the coasts of South & North
America towards the western Pacific is disrupted. This means that upwelling also stops (the rise of
very cold waters to replace the warm waters being moved westward). When this happens the
trade winds often reverse direction and warm water begins piling up along the coast of the
Americas. This reverses the normal patterns of dryness and precipitation—bringing extra powerful
storms and warmer temperatures to Southern California, but drought to Southeast Asa.
Chapter 6: Weather Systems
1. Defining weather
2. Air masses—large areas of air with uniform characteristics (temp & moisture)
3. Types of air masses—cA, mP, cP, cT, mT
4. Air masses move and when they do they bring their characteristics to the place they enter while
they are also changed by the conditions in the place they move into
5. Cold front—cold air advances on warmer air, lifting the warmer air rapidly, creating a steep
slope (gradient of lifting), rapid cloud formation, heavy rain, but short lived, followed by colder air
and temperatures. Cold fronts move quickly.
6. Warm front—warm air advances on cooler air, and the warm is lifted gently over the cooler air.
A gentle slope produces high-level clouds and then thicker stratus clouds, moderate rainfall for a
longer period of time, followed by warmer temperatures.
7. Occluded fronts—the cold front overtakes a warm front, lifting all warm air and creating cool
temperatures at the surface with some rain/snow for a longer period.
8. Midlatitude cylone formation—form along the polar front where cold and warm air masses
collide; in the beginning they have a clearly defined cold front and warm front but eventually the
cold front will overtake the warm front. Midlatitude cyclones move from west to east while rotating
in a counter-clockwise rotation as air converges on the low pressure.
9. Tropical cyclones—differ from midlatitude cylones as air masses in the tropics don’t have very
different temperatures, they move slowly, but have far more moisture. They also move from east
to west (opposite direction of midlatitude cyclones).
10. Hurricanes are able to power themselves through heat created by rapid condensation and
precipitation.
11. Hurricanes have an ‘eye’ or a vortex of sinking air with clear skies and fair weather.
12. Hurricane season is summer- as oceans heat up. Hurricane frequency is increasing as global
ocean temps get warmer.
13. Storm surges are one of the most dangerous impacts of hurricanes.
14. Tornadoes—form in tornado alley in the U.S. from Oklahoma through Illinois. Form here
because warm moist air from the Gulf collides with cooler air from Canada. There are few
topographic barriers to interrupt this convergence and the descending air from the Rockies creates
added turbulence and speed to the winds.
Chapter 7: Global Climate
1. What is climate
2. Climographs—show monthly averages of temperature and precipitation
3. What are the ‘controls’ or factors that control global temperature patterns? Latitude, location
(maritime vs continental) and elevation
4. What are the ‘controls’ or factors that control global precipitation patterns? Air masses
(sources), prevailing winds, ocean currents, topography, latitude and persistent high or low
pressure
5. Four patterns of rainfall: NONE (desert or semi-arid), summer maximum, winter maximum, or
year round.
6. Strahler climate types:
Tropical: 1, 2, 3, 7 4
Midlatitudes: 5, 6, 7, 8, 9, and 10
High latitudes: 11, 12, 13