Salt Lake Community College - Geography 1000
A. J. Allred, Adjunct
Student Name ____________________________
Mid-Term Exam
Answers and Explanations
1. Which of the following best describes the diameter of the earth?
a. Equal to about 1/3 of the distance around the equator
b. 8,000 times π
c. 24,000 times π
d. 24,800 divided by 7,900
e. Circumference times π
The relationship between any circle and its diameter is π or about 3.1. So, the diameter of the earth is about 1/3 of its
circumference.
2. Based on class discussion, which of the following represents the highest relative humidity?
a. 7/10
b. 6/8
c. 1/5
d. 2/4
e. 5/5
In class discussion, we have stated that the actual amount of water in a parcel or volume of air is absolute humidity,
actual water in the air. The relative humidity is that same amount of water compared to the capacity of the air -relative humidity tells us how full the “bucket” of air is?
A parcel of air with a capacity to hold five absolute units of water is “full” when there are five units of water in that
five unit bucket. All of the other fractions are relatively less than 5/5 which is 100%.
3. GPS compiles layers of data, while GIS provides position or location for that data.
True ___
False _X__
GPS stands for “global position” – tells you where things are. GIS represents “information” – usually compiled in
layers, one layer for each topic or category of data.
4. Ice releases heat when it melts into water.
True ___
False _X__
In order to for ice to melt it must absorb or collect heat. So, the melting process means that heat is transferred TO
water.
5. Water is unusual for which of several reasons:
a. Like many other substances, water contracts when frozen
b. Water has low capacity for heat absorption
c. Water is necessary for many, but not most living things
d. Weather and climate tend to be more severe in places that are near large amounts of water.
e. None of the above
None of the above is true. The opposite of each one is more true.
6. A location near the ocean will usually have a climograph with a relatively steep annual temperature curve.
True ___
False _X__
Water has an affinity for heat. Large bodies of water, such as oceans, collect heat when the air is warm, and release
stored heat when the air is cooler. So, living near the ocean tends to make climate more mild. Severe storms may
occur, but overall seasonal changes tend to be more mild than locations that are similar, except for being further
from the ocean or a large lake.
7. In Utah, cold fronts are common. They tend to move quickly from the east, bringing cold, descending air masses
that are usually dry and stable.
True ___
False _X__
Cold fronts do occur in Utah. But weather systems, such as storms, nearly always come from the west or southwest
because the jet stream and prevailing regional winds tend to blow from the west.
Further, stormy weather always involves low atmospheric pressure and rising air. Instead of stable and dry air, frontal
systems usually bring wet and turbulent air.
8. Atmospheric ozone:
a. is air pollution produced by chlorofluorocarbons
b. helps keep the surface of the earth warmer than otherwise
c. is corrosive, poisonous and noxious
d. b and c above
e. a and c above
Chlorofluorocarbons (CFCs) destroy atmospheric ozone, allowing more solar energy to reach the surface of the earth.
So, ozone tends to keep the earth’s surface cooler than otherwise.
In spite of protecting the earth, ozone is indeed corrosive and noxious. That’s why we want to keep ozone up in the
atmosphere where it can do its job. Ground-level ozone is just another form of air pollution.
So, we ought to avoid producing unnecessary ground-level ozone, and protect atmospheric ozone so that it can do its
job blocking harmful radiation from the sun. International agreements now ban the production of CFC chemicals that
may damage nature’s ozone layer.
9. Utah is dominated by which two general climate zones:
a. A and B
b. B and H
c. C and D
d. A and D
e. A and C, with some E
In class, we summarized world climates by considering the United States’ climate patterns. We divided the USA into
dry and wet halves, then divided the USA again by cold and warm halves.
Utah is not only dry but dominated by mountains. Dry climates are labeled “B” and mountains are labeled “H” (for
highland)
10. The continental United States exhibits two kinds of ‘B’ climate and at least three kinds of ‘C’ climate.
True _X__
False ___
The western half of the United States is mostly dry, with the northern half being relatively cool or cold and the
southern half warm to hot. There are at least three different mild “C”climate zones:
1. The Oregon-Washington coast
2. The Southern California coast
3. The bulk of the south-eastern states, such as Mississippi, Alabama and Florida.
All three of the mild “C” climate zones are fairly humid or at least located near oceans.
11. The change in climate resulting from moving thousands of miles further north or further south of the equator may
also be accomplished in a general way by moving closer to the coast of any ocean.
True ___
False _X__
According the textbook (and Mr. Allred’s climate rules), the further you go from the equator, the more severe climate
becomes. Likewise, the further you go from sea level or away from a large body of water, the more severe
climate becomes.
12. Hurricanes help ensure a relatively milder climate in equatorial regions and help prevent drought in many subtropical areas, including Florida.
True _X__
False ___
Hurricanes transfer vast amounts of energy from equatorial regions to locations further north or south. Also, Florida
and many sub-tropical locations, depend upon stormy weather to provide part of their annual water “budget.”
Without severe storms, many sub-tropical locations would experience drought, or water defecit. See questions
#40 and #33.
13. Which of the following options is/are represented by this generalized chemical relationship?
[hydrocarbons + water + carbon dioxide + solar energy => fuel and oxygen]
a.
b.
c.
d.
e.
Creation of carbohydrate fuels
Storage of sunshine and reduction of greenhouse gas
A warmer planet than otherwise
All of the above
Only ‘a’ and ‘b’ above
A tree is a ‘hydrocarbon’ that was created by sunshine acting on living things. So, solar energy is essentially stored in
the body of a plant. Likewise, food that humans eat was made through sunshine acting on plants.
So, plants grow by absorbing carbon dioxide and sunshine and water. That energy is absorbed or hidden in plants
until they are consumed (burned or digested as food). Storing solar energy in plants helps keep the earth cooler.
Burning fuels makes the planet warmer.
See also questions #34 through #37 below.
14. Solar energy reaching the earth’s surface is reduced:
a. when the earth is twice as far from the sun during winter months
b. by ozone depletion
c. by dust and other aerosols in the atmosphere
d. all of the above
e. none of the above
The earth is never “twice as far from the sun”. Ozone depletion would allow more solar energy to reach the surface of
the earth, not less. Dust and other aerosols may help cool the earth, by creating a screen or partial shade,
reflecting solar energy back into space.
See also question #19 below.
15. In Utah, what side of a mountain is more likely to be greener than the other options?
a. Northwest
b. Northeast
c. Southeast
d. Southwest
Class discussion and the textbook indicate that in Utah the sun is always somewhere in the southern sky. So, southfacing land tends to get more solar energy than do north-facing slopes. Water on a south-facing slope will
evaporate more quickly than will a shady slope.
Meanwhile, because wind and storms reaching Utah tend to come from the west, the west-facing side of mountains
should get more snow and rain that the east-facing “rain shadow” area on the lee side, away from the wind.
Taken together, in a dry place like Utah, the shady and rainy sides of a hill should be the most lush or green.
You can see that by looking at mountains around Salt Lake and elsewhere in Utah.
16. Citrus crops are found further north in Florida than in California because most of the U.S. southeastern states and
gulf coast are tropical ‘A’ climate zones.
True ___
False _X__
Florida does indeed have some genuine “A” tropical climate with abundant citrus crops. However, because Florida
and the entire southeastern United States is exposed to cold, dry wind from the high plains, damaging frosty
weather tends to occur more in Florida than in much of southern and central California.
So, citrus crops can be grown more reliably further north in California than in Florida.
All it takes in one hard freeze even once in a while to ruin a citrus grove. Many farmers just give up and go to some
place more reliable, like California, where cold, dry winds rarely invade.
17. Utah weather is dominated by:
a. Regional high pressure that tends to promote dry conditions
b. Local daily surface heating that provokes rising air and some clouds
c. Scattered small-scale instability with occasional thunderstorms
d. All of the above
e. None of the above
Rainy, humid weather does invade Utah from time to time, but high pressure, dry, sunny weather is the most common.
During the day, sunshine can cause “thermals” of rising air, but these seldom do more than kick up a few clouds
and “dust devils.”
18. Which of the following lines follow “great circles” of the earth?
a. the tropics of Cancer and Capricorn
b. any line of latitude
c. a typical, unadjusted time zone boundary
d. the Arctic Circle (or Antarctic Circle)
e. All of the above
A great circle route is any line drawn on the surface of the earth that would cut the earth in half if the line were to
continue all the way around in a circle.
The equator is the only line of latitude that goes all the way around the earth at the middle. Slicing the earth along the
equator would indeed cut the earth in half, with the cut passing through the center of the earth. The other lines of
latitude only cut a slice through the earth.
In contrast, any unadjusted time zone would cut the earth through the middle if that line were continued all the way
around and return to its starting point. A time zone is a north-south line of meridian that goes from pole to pole.
The other half of that line is twelve time zones away on the other side of the earth.
Like any other “great circle” route, a normal time zone is the shortest distance between the two poles.
19. The earth’s atmosphere acts as a type of “blanket” that keeps electromagnetic energy out and also keeps it in. So,
widespread volcanic activity could add enough dust and aerosols to the atmosphere to produce a widespread,
significant cooling period for much of the earth.
True _X__
False ___
The earth’s average temperature is a fine balance between absorbing heat and releasing heat. Anything that changes
that balance, even a little bit, can upset weather or even climate.
In past centuries, world-class volcanoes have thrown enough dust, ash, gases and vapors into the atmosphere to screen
out substantial solar energy for up to a year or more. During such periods, the average earth temperature was a bit
cooler than without such material blocking the sun’s rays.
See also question #14 above.
20. The inter-tropical convergence zone (ITCZ) is related to:
a. Masses of rising air and precipitation at about 30 degrees north and south latitudes
b. Year-round rain in high latitudes
c. Hurricanes and tornadoes at the equator
d. All of the above
e. None of the above
The “inter-tropical convergence zone (ITCZ) is centered near the equator. With a great deal of sunshine and water
near the equator, the weather tends to be mild and rainy. Rainy weather and storms are associated with low
atmospheric pressure and rising air.
Hadley cells represent circulation of masses of air, rising from the equator and moving north and south before
descending over deserts at about 30 degrees north and south of the equator.
At the far end of Hadley cells, descending air tends to be dry and warming as it descends, resulting in deserts or semdeserts, with little precipitation.
So, the ITCZ does not produce rising air at the far ends of Hadley cells.
There are no tornadoes or hurricanes at the equator because there is not enough cold/dry air nearby to provoke
warm/wet air to rise fast enough to create violent wind.
There is no year-round rain at high latitudes.
See questions #30 and #49.
21. During a weather inversion:
a. High mountain areas can be warmer than lower valleys
b. Valley air quality is often poor
c. There is relatively little chance of precipitation
d. All of the above
e. None of the above
A weather inversion results from a lack of daily surface heating, so that valley breezes do not rise to clear out stale or
dirty air. Weather inversions often occur during winter, when the sun is low in the sky, especially if mountains
surround a deep valley location. Without enough daily heat reaching the shadows, the air deep in the basin cannot
circulate, and just gets colder and colder.
Meanwhile, mountain tops may warm up quite a bit during the day, even in winter. During a sunny winter day, a ski
resort may have warmer, cleaner air that the bottom of the valley nearby, because the valley is cloaked in soot or
fog and can’t collect enough sunshine to warm itself and clear out the stale condition - - - until a genuine storm
comes along. That could take days or even weeks.
22. A “frontal” or “wedge” weather pattern can occur any time cooler, drier air meets warmer, wetter air.
True _X__
False ___
The key to severe weather is having enough heat stored in humidity to ‘push off’ and rise quickly against cooler, drier
air nearby. Humid air that can rise quickly will tend to condense out some of its hidden heat and re-warm itself
each time a cloud forms from rising and cooling. With enough humidity available, rising air can become very
fast. The fast air moves the more it can bring it yet more wet air, adding to the “chimney” effect, resulting in high
surface winds, heavy precipitation, and perhaps hail and lightning.
23. A region that spans nine time zones represents:
a. A little more than a third of the earth’s circumference at the equator
b. About nine hours at the Arctic Circle, or about 4.5 hours near the equator
c. About 135 degrees of longitude, at any latitude
d. Answers ‘a’ and ‘c’ above are both correct
e. Answers ‘b’ and ‘c’ above are both correct
With 24 hours in a day, eight time zones is 1/3. Each time zone represents 15 degrees of east – west longitude. So,
135 degrees amounts to nine time zones at 15 degrees each.
24. About half of the United States is characterized as:
a. A, tropical
b. B, dry
c. H, highland
d. D, continental severe
e. C, Mediterranean
As described in questions #9 and #10 above, the western half or so of the continental United States is somewhat dry.
There are mountains as well, but the dominant climate characteristic is ‘B’ for dry.
25. In North America, at about 40 degrees north latitude a city near the east coast of a continent will likely have a
more severe climate than a city on the west coast of that continent.
True _X__
False ___
With winds prevailing mostly from the west over North America, the mild conditions found along the west coast give
way to more severe climate and weather with distance away from the ocean. Moving eastward with the wind, the
northern interior of the United States turns dry and cold and then wet and cold before reaching the east coast.
Because weather at the east coast is influenced by colder, wetter air arriving from the continental interior, the east
coast will have a more severe climate rating than a place on the west coast at the same latitude.
26. Inside your house, standing near a window can have which of the following effects:
a. Air touching the glass can cool by conduction and then flow downward by convection to the floor
b. Radiation from inside the house can pass through the glass, causing a loss of energy to the outdoors
c. During the day, solar energy can radiate through the glass and be absorbed by solid objects on the inside
d. Solar energy can radiate through the glass and/or reflect off the glass and back into outer space
e. All of the above are true of the house, the window and the whole earth outside
A window in your home is very much like the earth’s atmosphere: solar radiation can pass through the glass just as it
passes through the atmosphere. That energy is either absorbed or reflected back out. Absorbed energy can be
transferred by conduction (direct touch) or by convection (air or water circulation).
So, air that is in contact with a cold window may get colder and then sink to the floor. Meanwhile, dark surfaces
inside the room may absorb solar energy and become very warm, causing nearby air to move by warming and
becoming less dense and more buoyant.
To keep the room from over-heating eventually, the energy from radiation that entered the room during the day must
leave at night.
27. A climograph that shows a temperature curve with a substantial dip in the middle probably represents a climate:
a. In the tropics
b. In the northern hemisphere
c. Somewhere in South America
d. Somewhere along the Oregon coast
e. none of the above
A climograph starts in January and ends in December, so June/July is the middle. A dip in the middle indicates that
the location has its coldest temperatures during June/July, the opposite of what we experience in Utah’s northern
hemisphere location.
Places in South America will have summer in December/January and winter in June/July.
28. A climograph for a seaport near the Equator should show small variations in monthly average temperature and
precipitation.
True _X__
False ___
According to “Mr. Allred’s Climate Rules” being near the equator should provide relatively more mild weather.
Likewise, a seaport is right at the ocean, which also provides a moderating effect on weather and climate. By
definition, a sea port is also at sea level. So, there is every reason for weather to be fairly consistent and mild
year-round.
29. Many soils in Utah have a pH of about 8.0, and can be improved for farming by making them more acidic.
True _X__
False ___
Dry soil tends to have a higher, more alkaline pH, while wet soils and climates tend to exhibit more acidity. Utah’s
typical pH of about 8.0 will tend to become slightly more acid by simply applying water.
So, plants need water anyway, and moving to a more acid condition, such as 7.0 tends to promote better growing
conditions as well.
30. Wind tends to flow toward high pressure regions, and tends to flow away from low pressure areas, resulting in
deserts located at the ITCZ.
True ___
False _X__
The opposite is true. HIGH goes to LOW. Higher pressure pushes toward areas with less resistance. Rising air
at the ITCZ leaves room for other air to converge on the area. So, higher atmospheric pressure prevails at the
north and south ends of Hadley cells. That pressure moves air toward the ITCZ where it follows other air that
previously lifted off and moved north and south.
See question #49.
31. Air emissions from Utah power plants can contribute to acid soil and water conditions in Ohio and Pennsylvania.
The same is true from China to the United States.
True _X__
False ___
In the northern hemisphere mid-latitudes (like Salt Lake City at 40 degrees north) winds prevail from west to east.
So, air emissions from a Utah power plant should flow toward eastern U.S. states.
What “goes around comes around” so eventually those same westerly winds may bring Chinese air pollution across
the Pacific Ocean to the United States, and so on.
32. Nitrogen is vital to producing hydrocarbon fuels but can be a nuisance when those fuels are oxidized.
True _X__
False ___
Most of the atmosphere is nitrogen, so it goes along for the ride when we breathe in oxygen or when we burn air in
the engines of our cars and power plants. The result is that nitrogen can get chemically bonded to oxygen during
the combustion process – if the combustion temperature is high enough.
In our bodies, the ‘combustion’ temperature is only about 98.6 degrees, so nitrogen that we breathe just goes back out
again when we exhale. However, in our cars and power plants, combustion temperatures can reach 2,000 degrees,
causing nitrogen to “oxidize” or chemically bond to oxygen.
The result is that oxides of nitrogen are another form of air pollution that we wish we didn’t have to create when we
burn coal or drive our cars. Oxides of nitrogen can be poisonous and corrosive and acidic, contributing to acid
rain that harms almost everything downwind.
See question #32 above.
33. The islands of Great Britain have a milder climate than locations at the same latitude that are deep within large
land masses.
True _X__
False ___
Great Britain is located much further north than places like Chicago and Salt Lake City. As such, its climate would be
much more severe (especially colder winters) were it not for the ocean currents that circulate around the islands.
Warm ocean that move north from equatorial regions provide heat while other ocean currents carry cold water
(and ice bergs) toward warmer southern regions.
The result is that oceans tend to help make cold places warmer – and warm places cooler (instead of over-heating).
See questions #12 and #40.
34. The main source of energy for electric lighting in this classroom is:
a. from nature’s ancient storage of solar electromagnetic energy in rocks
b. not from nuclear power, photo-voltaic or wind power
c. from fossilized remnants of old lake beds and swamps
d. not from geothermal heat from the earth’s interior
e. all of the above are true statements
Solar energy helps plants grow, with solar energy being “stored” as hydrocarbon plant material. Burning fossil fuels
represents the combustion of very old plants and animals that were grown by solar energy millions of years ago.
Many fossil fuels are found in ancient lake beds and swamps that are now parts of high mountains.
Nuclear power is important, but no energy from “nukes” is supplied directly to Utah.
Geothermal energy sources are important in Utah, but provide only a small fraction of all electric lightning energy
needs.
See also question #13 and questions #35, #36 and #37 below.
35. Which of the following pairs of earth elements is coming out of fossil ‘storage’ and being blamed for alleged
global warming?
a. nitrogen and oxygen
b. carbon and nitrogen
c. hydrogen and oxygen
d. carbon and hydrogen
e. oxygen and carbon
Hydrocarbons (some can be called “carbohydrates”) provide fuel for people, animals and machines. Aside from food,
fossil fuels supply most of our modern energy needs. Fossil beds composed primarily of carbon and hydrogen
compounds take the form of petroleum, coal and natural gas. See also question #34 above.
36. Which combination of nature’s elements is most associated with electricity generation?
a. carbon and nitrogen
b. nitrogen and sulfur
c. hydrogen and sulfur
d. oxygen and nitrogen
e. hydrogen and carbon
See questions #34 and #35 above. Nitrogen and sulfur are often burned along with fuel in engines, however, they are
mostly accidental, not essential to the combustion process.
37. Which of the following is not true:
a. Oxides of nitrogen are an incidental result of burning fossil fuels at high temperatures
b. Oxides are an essential part of the carbon cycle wherein solar energy is stored and then combusted later
c. Riding a bicycle is no better for the environment than driving a car because both activities involve
combustion, oxidation and production of greenhouse gases
d. Fossil fuels represent a form of “stored sunshine” from time periods when plant growth was heavy
e. Natural gas cars produce most some of the same types of ‘air pollution’ as do gasoline and diesel cars.
All of the above options are true except ‘c’. Riding a bicycle does indeed require respiration of atmospheric gases
and chemical decomposition of fuel (food). The big difference is two-fold:
1. A bicycle and rider weigh a lot less than an automobile, so there is vastly more air emission and air pollution
caused by cars than by bicyclists.
2. The combustion temperature in a car engine is high enough to produce oxides of nitrogen and sulfur that
constitute severe forms of air pollution, contributing to acid rain and even helping produce corrosive ozone at
the ground level where it can cause substantial damage to almost everything.
38. If ice floating on the ocean melts due to climate change, the result will be a rise in sea level.
True ___
False _X__
Ice that is already floating in the ocean is only on the surface because it is less dense when frozen. As soon as it
melts it returns to the normal density of ocean water. No change in overall ocean level occurs because the ice was
already in the water.
Of more concern is that the melting of pack ice (floating ice) will reduce the amount of reflective white covering
over high-latitude oceans, allowing sea water to absorb and hold more solar energy. As oceans warm, more ice
will melt, leaving yet more dark ocean to absorb more solar energy.
Eventually, land ice may melt, sliding into the ocean and causing a genuine rise in ocean level.
39. Hail storms occur because water droplets and ice particles get blown back up into cumulo-nimbus clouds, causing
small hailstones re-freeze new layers until they are so heavy that they finally fall to earth.
True _X__
False ___
Stormy weather is almost always about rising air and low or falling atmospheric pressure. Rapidly rising air can catch
ice, hail or rain droplets and blow them back up into storm clouds, allowing yet another layer of ice to form on
them.
Eventually, hailstones gather so many layers of ice that they are too large to be blown back upward.
40. Tropical regions near the Equator would be much hotter were it not for hurricanes, ocean currents, clouds and
Hadley cells that tend to move heat away from where regions where incoming solar energy is strongest..
True _X__
False ___
The presence of large amounts of water near the equator provides an opportunity for solar energy to evaporate
large amounts of water into vapor. Evaporation is a cooling process for equatorial regions and also provides
frequent cloud cover that reflects substantial amounts of solar energy back into space.
Wind and ocean currents also move large amounts of heat away from the tropics in the form of warm water and
water vapor, both of which contain vast amounts of heat. See questions #12 and #33.
41. An increase in world average surface temperature:
a. is more likely to be noticed in the Artic where ice is melting rapidly, turning white surfaces to dark
b. will mean more precipitation, but even more evaporation in continental interiors
c. will not be noticed as much in Arizona and in the Tropics
d. All of the above
e. None of the above
In polar regions, warming appears to be occurring more rapidly than at lower latitudes because white ice is
converting to dark water, allowing a rapid increase in solar energy absorption.
Deserts are already dry and without significant available water, have relatively little basis for absorbing more or
less solar energy than in the past.
42. A storm front that includes a “dry line” boundary can produce some of the world’s most dangerous weather.
True _X__
False ___
Air that is humid and warm is already buoyant. When confronted with cooler, drier air, that buoyancy is
magnified, resulting in rapid acceleration of rising air, and provoking very high ground-level wind speed. This
process can feed on itself: the more air rises the more it can condense out water vapor and release the hidden or
latent heat held by that vapor. By warming itself over and over, humid air can provoke tornadoes and some of the
highest wind speeds known anywhere on earth.
This kind of turbulence can also provoke lightning and hail along with causing tremendous damage to buildings
on the ground.
43. Which of the following combinations is most likely to produce a tornado associated with “dry line” conditions:
a. 88°F and 55% humidity on one side and 96°F and 80% on the other side
b. 60°F and 45% humidity on one side and 60°F and 65% humidity on the other side
c. 40°F and 65% humidity on one side and 50°F and 45% humidity on the other side
d. No combination above is different enough to provoke stormy conditions
e. All of the above are substantial enough to produce violate weather
The higher the air temperature, the greater the air capacity to hold humidity. When both air masses are very warm,
they both can hold enough energy to provoke their own individual storms. The fact that 96 degree air has nearly
double the capacity to hold moisture than 88 degree air also suggests a stronger differential between relatively
“dry” air and relatively “humid” air. That contrast adds further to the potential for a vigorous “dry-line” storm.
None of the other combinations of contrasting heat and humidity are nearly as strong.
44. Clouds are often flat on the bottom and rough on the top because:
a. The cloud bottom represents the lowest altitude where the humidity “bucket” becomes full
b. The cloud top shows the boundary between drier air above and wetter air below
c. Clouds often form when air rises to the point where water vapor condenses and becomes visible liquid
d. At the cloud base, actual air temperature is equal to dew point temperature
e. All of the above
These answers should be self-explanatory.
45. On a normal day:
a. Lower elevation surfaces heat-up very little, producing air stability.
b. Air tends to be stable, with heavier, cooler air always below and sun-warmed air always aloft.
c. As the day warms, winds blow inland from oceans to replace air that is heated and rising over land.
d. Air quality is likely to better on a day in which air temperature is ‘inverted’ and stable.
e. All of the above are true.
All of the options above are flawed in some way, except option ‘c’. On a normal day, there is usually some surface
heating, causing air to rise and be relatively unstable. By nightfall, cooler air aloft tends to subside and the cycle
begins again the next day.
On an inversion day, air quality is likely to be poor, due to lack of circulation.
46. Relative humidity tends to go down at night because the air cools and loses some of its capacity to hold vapor.
True ___
False _X__
Relative humidity will rise when air temperature goes down, because cooler air has less capacity to hold a given
amount of water vapor. At night, with the same absolute moisture available, relative humidity will rise because the
“bucket” has gotten smaller due to lower air temperature.
47. Oceans are becoming more alkaline from air pollution. Oceans are also warming slightly.
True ___
False _X__
It is true that oceans are warming slightly; however, oceans are also becoming more acidic due to rising levels of
carbon dioxide available for absorption by the atmosphere and oceans.
48. Fog can be produced any time humid air encounters a surface that is cold enough to cause the air to reach its dew
point temperature. On a sunny day, actual air temperature is higher than dew point temperature.
True _X__
False ___
Water vapor (humidity) is generally invisible. When air cools enough for dew point to be reached, then the air
“bucket” is full and vapor converts back to visible liquid water.
So, to create fog, all that needs to occur is for a cold surface to contact humid air, or for cold air to pass over warm
water. When dew point temperature is reached, condensation occurs, the opposite of evaporation. Evaporation
causes liquid water to disappear into vapor. Condensation—cooling causes that vapor to re-appear again as liquid
water.
49. The Inter-tropical Convergence Zone is part of Hadley cell circulation that:
a. Helps create deserts at 30 degrees north and 30 degrees south of the equator
b. Provokes rainy, cloudy weather near the equator
c. Tends to migrate southward from June to December
d. Helps provide at least some rainy weather in Utah and Arizona
e. All of the above are true
See questions #12, #20 and #30.
50. The jet stream moves from west to east, bringing weather changes that can include::
a. High-pressure cells and ridges that bring sunny weather
b. Low-pressure cells that tend to bring turbulent, stormy or cloudy weather
c. Moisture that is ‘pulled’ in from the south by high-pressure cells that feed into low pressure cells
d. Storm types that include orographic, frontal, or convective
e. All of the above are true
The optional answers in this question explain themselves.
Optional essay questions for extra credit:
1. Why does a can of compressed air get cold when you release pressure by spraying
When the can was filled with compressed air, that compressed concentrated whatever heat was in the air, so the can was
probably hot for a while. When the can is sprayed, pressure is released, causing an opposite effect: whatever energy was in
the can (temperature) is now decompressed, or de-concentrated, so its temperature would drop as available energy is now
spread over a larger area.
A can of compressed air can actually collect ice on the outside because the temperature of its contents dropped enough to
cause water vapor outside the can to cool, condense into liquid and then freeze by conduction (direct contact).
2. Describe how Utah experiences any or all of the four types of precipitation or ‘storminess.’ Use words, drawings
and/or labels.
Mountains in Utah require that wind rise in order to go over the top. Rising air automatically cools down as it decompresses
with lower air pressure at higher altitude. Eventually, the air cools off enough to reach dew point temperature -- a cloud
forms. If the air continues to cool down, then eventually precipitation will fall out of the cloud.
In a real sense, the other three types of precipitation are similar: something causes the air to rise, decompress, cool down,
reach dew point, condense out moisture and then precipitate.
Frontal storms involve buoyant, warm/wet air riding over the top of cool/dry air that is more dense and heavy. The cool/dry
air acts as a sort of artificial or invisible mountain over which warm/wet air must rise.
Convective storms involve air masses that rise on their own simply because they are full of warm and wet air, both of which
are buoyant. They have so much heat and humidity in them that they don’t need a mountain or a mass of cooler/drier air to
cause them to rise.
Convergent storminess is just a form of convective activity in which two air masses collide and rise together if they are both
warm and humid enough.