Chapter 3
The Climate System: Controls on Climate
2. How does position on a continent affect the climate of a location?
Answer: Continental position affects the climate of both interior and coastal areas. Locations adjacent to
water bodies generally experience a delay in the onset of seasons and milder temperatures throughout the
year due to the storage and release of energy from water bodies to the atmosphere. Because water
temperatures remain relatively stable over time coastal locations will see more constant temperatures
throughout the year. Interior areas of continents warm significantly in summer and cool dramatically
during the winter, resulting in a large seasonal temperature range. The climates of interior locations are
not moderated by a large body of water and thus experience more cold-air outbreaks and heatwaves.
4. Discuss the important characteristics of earth’s orbit.
Answer: The earth’s orbit creates a noticeable impact on earth’s temperatures when combined with other
factors. The orbit around the sun is elliptical and not circular. This results in variability in earth-sun
distance throughout the year. The earth-sun distance affects the severity of the winter and summer
seasons. The earth’s distance from the sun alone has a minor influence in controlling intraannual surface
temperatures; otherwise July would be warmer in both hemispheres when the earth is closest to the sun.
The changing orientation of the earth’s tilt relative to the position of the sun as the earth revolves around
the sun is the cause of the seasons.
6. How does parallelism play a role in seasonality?
Answer: The principle of parallelism states that the axial tilt of the earth remains the same as it revolves
around the sun. The northern hemisphere’s axis of rotation always points toward the North Star.
Parallelism affects seasonality because each hemisphere will be pointed toward and away from the sun
during its annual revolution around the sun. These conditions result in significant differences in the
amount and intensity of insolation received at the surface during the course of a year. The northern
hemisphere experiences an energy surplus when the southern hemisphere is in an energy deficit and vice
versa.
8. How do earth-sun relationships affect the spatial and temporal distribution of energy through the year
for each hemisphere?
Answer: The tilt of the earth, its daily rotation on its axis, and its annual revolution around the sun create
significant differences in insolation received at the surface throughout the year. During the course of a
year each hemisphere receives an energy surplus when pointed toward the sun and an energy deficit when
pointed away from the sun. The changing orientation of the earth’s tilt relative to the position of the sun
as the earth revolves around the sun is the cause of the seasons. The northern hemisphere is pointed
toward the sun during the months of June, July and August while opposite conditions occur in the
southern hemisphere. The warmest months of the year generally occur for locations that are pointed
toward the sun and receiving a greater number of sunshine hours and more direct solar rays. Differences
in day length increase with increasing distance from the equator.
10. How does specific heat compare between water and land surfaces?
Answer: The specific heat of water is about five times greater than that of land. This means that given the
same mass of land and water, water will require five times more energy to heat to the same temperature as
land. Due to the high specific heat of water, it takes five times longer to heat up and cool down as
compared to land areas.
12. How are winds, and the forces involved, in the free atmosphere similar to/different from those at the
surface?
Answer: Wind speed and direction is a function of four forces: pressure gradient force, the Coriolis
effect, centrifugal force, and friction. Surface winds are typically much weaker than winds in the free
atmosphere due to the strong influence of friction. Friction is an opposing force which acts to decrease the
speed of moving objects. The effects of centrifugal force and the Coriolis effect are reduced near the
surface because they are both dependant on wind speed. The effect of friction is reduced with height and
causes wind direction to shift with increasing altitude. Winds are much faster in the free atmosphere
because they are minimally affected by friction. The increased wind speeds enhance the influence of
centrifugal force and the Coriolis effect in the free atmosphere. Winds in the free atmosphere typically
flow parallel to the isobars as the forces that influence wind speed and direction become balanced.
14. What role do surface ocean currents play in climate?
Answer: In general, surface ocean currents have the most important and immediate effects on the climate
of a region. Ocean currents affect the climate of a location through their ability to transport huge
quantities of heat and moisture. Surface ocean currents are driven primarily by surface winds. When
surface winds move water offshore a vacuum is created and pulls water upward from beneath the surface.
Upwelling greatly contributes to the climate of coastal locations because of the cold water that is brought
to the surface. The proximity to a cold or warm surface ocean current has a strong influence on a region’s
climate. Cold ocean currents are located on the western side of a continent and warm ocean currents are
found along the eastern side of a continent.
16. Are thermohaline currents important to climate? If so, how?
Answer: Thermohaline circulation is a very slow energy transportation that influences the climate on a
global scale. Thermohaline currents are extremely effective at redistributing heat around the globe,
supplying heat to the polar regions and thus regulating the extent of sea ice in these regions. Thermohaline
currents strongly influence the climates of coastal areas through their ability to supply large quantities of
energy to a region.
18. What local features may influence the climate of a location? How?
Answer: Local features can influence the climate of a region in several ways. Examples of local features
include lakes, wetlands, forests, agricultural areas, and urban areas. Lake effect snows are common over
the Great Lakes region during winter when cold, dry winds blow across the relatively warm lake waters.
The additional energy associated with cities creates a phenomenon known as the urban heat island. Urban
areas can be much warmer than the surrounding environment because of a combination of factors that
emit heat into the local environment. The effects of pollution on surface temperature are still not
completely understood.