Salt Lake Community College
Geography 1000 – Physical Geography
AJ Allred, Summer, 2015
Student Name ___________________
Quiz 4
Explanations
1. Evaporation is an effective way of absorbing or ‘hiding’ heat so that it can be carried away by
convection. One result is severe storms in places far from the Equator. Precipitation that originated
by evaporation in the tropics helps prevent drought in places like Florida.
True ___
False ___
Explanation for Question 1. Chemical cohesion that bonds water molecules together as liquid can be broken if
enough energy is absorbed: kinetic vibration or oscillation increases as temperature increases. So, when enough
heat is available to break cohesion bonds liquid goes to vapor -- water evaporates.
That energy is not lost; it is just hidden in the vapor. So, temperature drops as heat is absorbed in the process of
breaking cohesion bonds when liquid is ‘vaporized’. Evaporation is a cooling process. That is why we use
“swamp coolers” that evaporate water, causing temperature to drop as the “price” paid for vaporizing liquid to
vapor.
So, when condensation occurs, vapor returns to liquid state. Energy that was hidden, or latent, returns to
“sensible” heat that we can sense or feel or measure with a thermometer.
Evaporation is the process of “hiding” heat and “hiding liquid” as invisible vapor. Condensation is the process
of returning invisible vapor to clouds of liquid water we can see, and heat that we can feel again as
“temperature”.
2. In the Earth’s atmosphere, what is the closest estimate of the average weight of all vapor and gases?
(Hint: about 99% of atmospheric gases are either nitrogen or oxygen)
a. 29
b. 44
c. 48
d. 52
e. 76
Explanation for Question 2. Nitrogen accounts for 78% of Earth’s atmosphere and is in the molecular form of
N2, with each atom having an atomic weight of 14 for a total weight of 28. Oxygen in the atmosphere also
appears as a pair, with each atom having an atomic weight of 16, for a molecular total of 32. Together,
atmospheric nitrogen and oxygen account for at least 99% of atmospheric weight. The average weight of this
fraction should be about 29 because of nitrogen’s relative dominance.
Ozone is made of three oxygen atoms for a weight of 48; carbon atoms weigh 12 and hydrogen has an atomic
weight of just one.
3.
Places near the ocean tend to have milder seasonal temperatures than inland because:
a. The sun’s electromagnetic energy penetrates bare dirt and rock better than dark oceans
b. Land surfaces can absorb more solar energy than water bodies
c. Water has high capacity for absorbing heat and then radiating it back out later
d. Land areas far away from water tend to exhibit more stable air temperatures than do oceans and
lakes during daily and seasonal temperature swings
e. All of the above are true
For Question 3: Dirt is opaque and usually dark in color, so solar energy is easily absorbed, but only at the
surface. The result is that dry lands heats up quickly during the day, and cools quickly at night, as if it were a
“small battery”. Each day, it tends to fill up quickly and “overflow” with heat radiation going back out early in
the day. If you touch a black car or asphalt on a hot day, you can experience how quickly thin, dark objects
“overflow” and send heat back out into the sky.
Water is mostly clear, so it can absorb vast amounts of energy without changing temperature. So, places near
oceans tend to be mild: oceans “take the heat” for you. After absorbing heat all summer, oceans then radiate
that energy “storage” back into the air when it can help coastlines stay mild.
According to “Mr. Allred’s Climate Rules” it not only helps to be near large water bodies, but it also helps to
have the wind blow from the water to land, so that mild conditions over water get shared a bit.
Being far inland reduces the softening effect of oceans.
4. Because of Coriolis force and the “Trade Winds”, a hurricane that develops in the Atlantic Ocean will
tend to move westward toward the United States and Mexico. A hurricane in the Pacific Ocean will
tend to move westward also, which moves it away from Los Angeles and northern Mexico.
True ___
False ___
For Question 4: Trade winds result from Coriolis force deflecting winds to the right in the northern hemisphere
and deflecting winds to the left in the southern hemisphere. So, in the northern hemisphere winds appear to
move in a circular pattern, to the east across the top, and toward the west along the bottom. The reverse is true
in the southern hemisphere. Thus, Coriolis winds in both hemispheres combine near the equator to push
westerly.
So, trade winds push hurricanes toward the USA on the Atlantic side, and push hurricanes away from the USA
on the Pacific side. This wind pattern is illustrated well in the textbook. So, the west coast of North America
seldom experiences strong hurricane effects because severe storms originate over ocean and are then pushed
westward, away from land.
5. Radiation is the only way that energy can leave the Earth. Other means of energy transfer, such as
conduction and convection require energy stored in substances, or mass. There is no real mass
between Earth’s atmosphere and the Sun. Direct contact with something (touch) allows energy as
kinetic motion to be transferred from a warmer (more kinetic vibration) to something colder (less
kinetic motion).
True ___
False ___
For Question 5. Convection is fluid motion, whether air or water, as energy in the fluid transfers along with the
host substance. Conduction is energy transfer by direct contact or touch. So, objects that are not moving can
still transfer energy by direct contact, such as electricity being conducted through a stationary wire. The wire
does not move, but instead just allows energy to pass through. In contrast, steam rising is a fluid in motion,
transferring energy along with itself by convective movement.
Because there is no fluid or solid substance in outer space, there is no way that energy can be transported by
conduction or convection. Only by electromagnetic radiation can energy pass through empty space. Reflection
is a form of radiation. So, sunlight “bouncing” off a shiny surface is a form of radiation that allows solar energy
to go back into outer space.
6. For solar energy that reaches the Earth:
a. the most intense or most energetic rays or waves are visible by human eyes
b. most waves are short wave length and easily penetrate the atmosphere
c. about 1/3 of all solar energy is not absorbed by Earth or its atmosphere
d. portions of the violet and red parts of the spectrum are visible by human eyes
e. All of the above are true
Explanation for Question 6. According to the textbook, visible light (colors of the rainbow) are in the range of
wavelengths that human eyes are designed to see. Visible light is also the most intense part of the solar
electromagnetic spectrum and contains more than 40% of all solar energy reaching Earth.
Most incoming solar energy is relatively short in wave length, and most outgoing energy is in longer-wave or
thermal or infrared wavelengths. Shor wave lengths get in easily; long wave length energy leaves less easily.
That is why your car heats up while sitting in a parking lot. Short wave solar energy easily gets through your
windshield and then turns to longer-wave thermal energy that takes longer to escape. In fact, sometimes it takes
almost all night for your car to cool day after a whole day of sitting in the Sun. That is also why greenhouse
gases play an important role in whether or not Earth warms or cools over time. Greenhouse gases allow plenty
of solar energy to enter, but then tend to absorb or block it on the way back out.
About 1/3 of incoming solar energy is reflected back into space. It is not absorbed and does not convert to heat
or do any work before leaving.
Human eyes can see small portions of the ultraviolet and infrared energy spectra. They show up as the color
purple and some shades of red, such as when objects are heated in a fire until they are “red hot”.
7. Of the following means of energy transfer, which one prevents the Earth from over-heating?
a. Radiation
b. Reflection
c. Absorption
d. Conduction
e. Convection
Explanation to Question 7. Radiation is the only type of energy that can cross empty space, so it is the only
means by which energy can enter or leave the Earth’s atmosphere. Reflection is a form of re-radiation. So,
energy that is not absorbed gets reflected right back out into space. Reflected energy is not absorbed and
therefore does not convert from mostly short wave to most long wave (infrared or thermal energy as heat).
Remember that conduction is transfer of kinetic ‘vibration’ by direct touch or contact, such as electricity
passing through a wire. The wire does not move - only the electricity does. In contrast, convection is actual
movement of air, water or some other gas or fluid, carrying thermal energy with it. Putting your face over a
boiling pot will coat your face with watery heat - - that is convection. Unlike the copper wire in a wall that does
not move, convection does involve movement of smoke, gas, or liquid.
Other means of energy transfer require “mass” (substances) for heat transfer, such as steam that rises, or
electricity that conducts through a copper wire. There is no water or copper wire in outer space, so convection
and conduction do not help remove thermal energy from our planet.
8. If the overall albedo of Earth were to rise, which of the following patterns are probably occurring?
a. Ice is melting and the Earth is warming
b. Ice is accumulating and the Earth is cooling
c. More solar energy is being reflected back into space
d. Answers ‘a’ and ‘c’ above are both true
e. Answers ‘b’ and ‘c’ above are both true
For Question 8. Albedo means reflectivity. Shiny white snow or ice is highly reflective, so its albedo is often
higher than 90. The color black is highly absorptive, so its albedo is sometimes less than 10%, or in other
words, only 10% reflective and about 90% absorptive. That is why an asphalt parking lot can become too hot to
touch in the summertime, whereas a snow field can be very cold. That is also what is matters a lot when ice and
snow melt into dark water: that is the worst possible combination for absorbing more solar energy than we need.
If the overall albedo of Earth were to rise, then more energy is being reflected into outer space. More reflection
means less absorption, so Earth should become relatively cooler as albedo rises.
As described in the book and in class discussion, if the Earth is cooling then less ice is melting, leaving, helping
to create a positive feedback loop: the more ice the more cool; the more cool the more ice.
By definition, there is nothing in a positive feedback loop that would inherently slow down or stop its tendency
to reinforce its own effects. Positive feedback loops tend to “spiral out of control”. The more we melt ice and
snow, the more we absorb heat instead. The more we absorb heat the more we can melt ice. There is nothing in
natural Earth systems to stop that positive feedback loop.
9. Arizona is not close to the Equator, which explains why equatorial regions are so much hotter in
summer than Arizona.
True ___
False ___
Explanation for Question 9. Equatorial regions are cooler than Arizona during summer. In fact, equatorial
areas really don’t have any seasons, because the Sun is always high in the sky and there is plenty of water along
the Equator to absorb solar energy.
As water absorbs solar energy it also tends to evaporate, and then eventually cool and condense back into
clouds of liquid water. Clouds are white and opaque, so they reflect solar energy back into space, which also
helps keep equatorial regions warm instead of hot.
So, it is true that solar energy is more intense near the Equator, because the sun is overhead most of the time;
however, cloud cover and surface make conditions much cooler than places like Arizona that lack water to “take
the heat for them.”
Even at night, the Equator is milder than Arizona because cloud cover also tends to re-radiate surface radiation
back to the surface. In any case, equatorial regions are never far from intense solar energy, so they never get
cold enough to need much cloud cover. Such regions will be milder no matter what.
10. Which of the following statements is/are true of air quality in Salt Lake valley?
a. Ground-level ozone rises in winter to protect us from harmful Uv rays
b. Atmospheric ozone becomes a serious air pollution problem during cold, dark winters
c. Ground-level ozone is produced in conjunction with sunshine and causes air quality alerts during
summer
d. Valley breezes become very strong in winter, causing warm air to leave our area
e. All of the above are true of air quality conditions in Salt Lake valley
For Question 10. Ground-level ozone is produced by air pollution in combination with solar rays and daytime
heat. Hot weather is more likely to exhibit hazardous levels of ozone. Atmospheric ozone, in the stratospheric
“ozone layer” is produced by solar energy striking oxygen molecules. Atmospheric ozone is a natural, healthy
condition that protects the surface of the Earth from dangerous ultraviolet energy.
In winter, there is plenty of air pollution but not enough solar energy and heat to produce hazardous levels of
ozone. Instead, the lack of solar energy and heat lead to “air inversions” because stale, cold air at the surface is
unable to rise as “valley breeze”. At the same, air aloft is usually sunny and fairly warm, compared to cold,
polluted air at the surface. Inversions are more common in winter; ozone pollution is more common in summer.
11. On Earth, unstable atmospheric conditions are normal. Stable conditions are not normal. Normal
daily valley breezes tend to help freshen the air and clear out air pollution. If valley breezes are
absent, then mountain breezes can help trap pollution. In fact, a weather ‘inversion’ means that air is
generally stable or sinking. Cold air could be accumulating in valleys. Surface air pollution may
accumulate as sinking air keeps valley conditions stable, calm and stale.
True ___
False ___
For Question 11. As shown in the textbook, Earth’s troposphere is turbulent and mixing because solar energy is
absorbed, caused changes in pressure that lead to air movement. Unstable conditions help freshen the air. An
air inversion is “inverted” or up-side-down in regard to temperature: air is normally warmer at the surface, so it
rises, and colder air aloft will sink to takes its place.
An inversion involves warm air above, and cold air at the surface. Warm air won’t sink, and cold air won’t rise,
so we have a layering that traps pollution at its source. -- the surface.
12. What is the best reasonable estimate of the portion of incoming solar energy that is absorbed by
oceans alone, separate from dry land?
a. 55%
b. 22.5%
c. 49%
d. 69%
e. 35%
For Question 12. In class we illustrated the numbers shown in the textbook for the distribution of solar energy
that reaches the Earth. Consider that 45% goes into dry land and oceans. Consider that oceans cover 70% of
Earth’s surface. On that basis, a good starting point for allocating solar energy to the Earth would be:
0.70 x 0.45 = 0.31. Of course, we know that water easily absorbs more of its share of solar rays, so oceans
really do account for more than 31% of absorbed solar energy. Some sources of information about solar
absorption estimate that Earth’s surface absorbs more than 50% of all incoming solar energy. So, the portion
allocated to water could be 35% or more.
13. Let’s compare daily weather in Salt Lake with daily weather at the beach in Los Angeles. Which of
the following statements is NOT true?
a. In Salt Lake, a valley breeze is comparable to an on-shore breeze in Los Angeles
b. A mountain breeze in Salt Lake valley is comparable to an off-shore breeze at the ocean
c. Valley breezes and on-shore breezes both tend to occur in the morning
d. Off-shore breezes and mountain breezes tend to occur in the evening or at night
e. A valley breeze and an on-shore breeze both occur at night when Earth is cooling
For Question 13. As shown in the book and in class, dry Earth easily absorbs daily solar energy and converts it
to heat that causes air to rise. Valley breezes go up from the valley. Likewise, on-shore breezes result from air
being drawn in from the ocean to land as warm air rises each day over heated land surfaces.
The reverse occurs at night, as dry Earth cools quickly while ocean does not. Cooling air sinks over land and
pushes out to sea – on off-shore breeze. In Salt Lake at night, cooling air sinks back to the valley floor.
14. The ‘adiabatic’ concept means that energy is lost or destroyed when rising air cools by
decompression. Adiabatic cooling disperses energy back into outer space, preventing the Earth from
over-heating.
True ___
False ___
Support for Question 14: The “adiabatic” concept means that a rising parcel of air will tend to expand as it goes
up, because air pressure decreases with altitude. A sinking parcel of air will tend to compress, so that energy in
the parcel is concentrated as the air sinks. Measured temperature in a rising parcel of air will tend to decrease,
while the temperature of sinking air will increase. The process can repeat endlessly as heat is concentrated or
diluted based on changes in air pressure. Adiabatic temperature changes are not about energy being destroyed
or created, but only about energy in air being concentrated and de-concentrated depending on air pressure.
15. Cloudy weather will differ from clear skies in which ways:
a. During cloudy weather, temperatures will be colder at night and warmer during the day than without
clouds
b. During clear days and nights, temperatures will be warmer at night and warmer during the day than
with clouds
c. During cloudy weather, day-time temperatures will be higher than during sunny weather
d. During cloudy weather, night-time temperatures will be the same as during the day
e. During cloudy weather, nights will be warmer and days will be cooler than without clouds.
Explanation for Quiestion 15. As we discussed in class, clouds reflect solar energy back into space, so day-time
temperatures tend to be cooler. At night, clouds absorb and radiate surface thermal energy back to the surface,
making night-time temperatures warmer. Some of the coldest nights in Utah are when skies are clear.
Compared to Utah, the tropics are understandably warm and mild, not hot—cold, because vast ocean water
absorbs vast solar energy and produces frequent cloud cover, both of which help make the tropics mild.
16. A solar ray (or wave) that enters the atmosphere at sunset must pass through a thicker cross-section
of atmosphere than a ray or wave that strikes the Earth at a more vertical angle at noon. So, places
like Alaska may have long summer days but solar energy must still pass through so much atmosphere
that a substantial portion never reaches the Earth’s surface.
True ___
False ___
Explanation for Question 16 above. As shown in textbook pictures, the atmosphere may be only about 100
miles thick, but a solar ray entering at a very shallow angle will have to cut through a wide cross-section of
atmospheric gases in order to reach the surface. So, not only do high-latitude locations receive less solar
energy, a larger portion of that incoming energy does not successfully pass through the atmosphere to reach the
surface. So, even during “midnight sun” summer days when sunshine is available for more than 20 hours,
surface air temperatures are never very warm.
17. A climograph for Salt Lake City compares to a climograph for Los Angeles in the following ways:
a. Salt Lake will have a steeper annual temperature curve than Los Angeles
b. Salt Lake will have a flatter or more shallow temperature curve than Los Angeles
c. Both cities will have a very similar temperature curve because both cities are located in the dry,
sunny western United States
d. None of the above are true
e. All of the above are true
Explanation for Quesiton 17 above. “Mr. Allred’s Climate Rules” indicate that Salt Lake City should have
more severe temperature swings than Los Angeles because it is located deep within a continental land mass and
does not enjoy the moderating influence of ocean water that is found near coastlines. So, there will be more
daily temperature variation and more annual average temperature variation in Salt Lake City. Likewise, the Salt
Lake area is not near sea level, nor near the Equator, so it ‘fails’ at three out of four rules for climate mildness.
Wind direction makes a little difference, because we do get some influence from westerly winds arriving from
the Pacific coast. But we are too far away to have a ‘balmy’ (mild) climate like Portland, Oregon, San
Francisco or Los Angeles.
18. World-wide atmospheric carbon dioxide levels:
a. Increase during winter in the northern hemisphere
b. Increase during the growing season in the northern hemisphere
c. Decrease from September through March everywhere on Earth
d. Decrease during summers because automobile traffic volumes are much lower
e. None of the patterns above are accurate.
Explanation for Question 18 above. Living plants absorb carbon dioxide during growing season. Most Earth
land masses are in the northern hemisphere where seasonal variation leads to similar variation in carbon gas
absorption. During a growing season, living plants absorb a great deal of carbon dioxide. So, during northern
hemisphere summers, carbon gas levels world-wide tend to subside.
Oceans also absorb carbon gases, but not with as much seasonal variation as over large continental land masses,
most of which are located in the northern hemisphere. So, the highest annual level of atmospheric carbon
dioxide should occur during northern hemisphere winters when plant growth is minimal.
Unfortunately, exhaust emissions by humans continue year-round, so “Mother Nature” falls behind in CO2
absorption. In the pre-industrial era, Earth CO2 levels hovered around 280 ppm (parts per million), helping keep
average Earth temperature at about 59°F. At present, Earth atmospheric CO2is above 400 ppm, so we have
reason to believe that average Earth temperature is rising.
19. Air that contains water vapor tends to rise because it is lighter weight than dry air. Warm, humid air
is a great combination for a storm, including hurricanes, cyclones and even tornadoes. Warm wet air
contains vast amounts of energy that contribute to high winds, lightning, hail, and heavy
precipitation. Even a winter blizzard can be windy because vast amounts of energy are stored in
frozen snow and ice.
True ___
False ___
Support for Question 19. This concept is introduced only very lightly in Chapters 3 and 4. We will need more
information to adequately understand the concept of storminess arising from warm versus cool air - - and high
pressure versus low pressure. For now, we have mentioned that vast amounts of energy exist even in an icy
blizzard, because air at -20 F degrees is still hundreds of degrees above absolute zero. Meanwhile, we also
know that warm air rises because it is less dense: more kinetic activity in atmospheric gases causes gas
molecules to push apart: less dense = lighter weight. Light weight gases rise. We also know that water vapor is
lighter-weight than dry air so, warm and wet air will rise quickly.
Coriolis force tends to make moving air turn to the right, you might say putting “spin on the ball.”
20. Wind moves from high pressure to low pressure. Rising air creates low pressure that draws in more
air from higher pressure nearby. Coriolis force deflects wind to the right, but pressure gradient plus
Coriolis result in low-pressure air turning to the left (counter-clockwise in northern hemisphere).
True ____
False ___
Support for Question 20. Rising air leaves room at the surface for heavier air to move in and take its place. As
air moves it is deflected to the right in the northern hemisphere. We will study cyclonic, or right-turning air in
more detail later.