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343 Cards in this Set
- Front
- Back
Weather and climate are expressed in terms of the same basic ______ The most important elements are _____ |
Elements (1) air temperature, (2) humidity, (3) type and amount of cloudiness, (4) type and amount of precipitation, (5) air pressure, and (6) the speed and direction of the wind. |
|
What is air? |
a mixture of many discrete gases, each with its own physical propertie |
|
Which two gases mostly make up 99% of air? The other 1%? |
nitrogen and oxygen—make up 99 percent of the volume of clean, dry air. 1% is argon and other gases |
|
About _____ % of additional c02 from fossil fuels remains in the air
|
45% |
|
Estimates project that by sometime in the second half of the twenty-first century, CO2 levels will be ____ |
twice as high as the pre-industrial level. |
|
Humidity is a reference to __________
|
water vapor in the air. |
|
Water vapor is the source of all _______ |
clouds and precipitation |
|
When water changes from one state to another it absorbs or releases heat. This energy is termed _______ |
latent heat |
|
water vapor in the atmosphere transports _______ from one region to another |
latent heat |
|
tiny microscopic solid and liquid particles in the atmosphere are called _________ |
aerosols |
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Aerosols are significant because they act as surfaces on which ________________
|
water vapor can condense, an important function in the formation of clouds and fog. |
|
Aersols can _______________ solar radiation |
absorb, reflect, and scatter |
|
the varied hues of red and orange at sunrise and sunset can be contributed to ______ |
aerosols |
|
Ozone is a ________
|
form of oxygen that combines three oxygen atoms into each molecule (O3) |
|
Ozone is concentrated in the ______ its distribution is not ________ |
stratosphere, uniform |
|
In the stratosphere, ozone is created when __________ |
oxygen molecules (O2) are split into single atoms of oxygen (O) when they absorb ultraviolet radiation emitted by the Sun. Ozone is then created when a single atom of oxygen (O) and a molecule of oxygen (O2) collide. |
|
Ozone absorbs _________ |
UV radiation from the Sun. |
|
Ozone is regarded as a pollutants when produced ______ |
at ground level |
|
Photochemical smog results from when _______ |
strong sunlight triggers reactions among pollutants from car exhaust and industrial sources. |
|
chlorofluorocarbons (CFCs) are known to ___ |
deplete ozone |
|
CFCs reach the upper atmosphere because they are _________ |
inert (that is, not chemically active) in the lower atmosphere |
|
When CFCs reach the upper atmosphere sunlight ______. The ______ released this way _________ |
separates the chemicals into their constituent atoms. chlorine atoms, break up some of the ozone molecules. |
|
In addition to skin cancer, UV radiation also can impair the _________ as well as promote _______ |
human immune system, cataracts |
|
The ______ protocol was developed to combat the use of CFCs |
Montreal Protocol |
|
CFCs are expected to remain active in the atmosphere until between __________ |
2060 and 2075 |
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The rate of pressure decrease with increase in altitude is not constant. Pressure ___________ near Earth’s surface and ________ at greater heights. |
decreases rapidly, more gradually |
|
One half of the atmosphere lies below an altitude of _____ |
3.5 miles |
|
At about 10 miles, ______ percent of the atmosphere has been traversed |
90% |
|
We divide the atmosphere vertically into _____ on the basis of __________ |
four layers, temperature |
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The lowest layer of the atmosphere is the ______
|
Troposphere |
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Essentially all important weather phenomenon occurs in the _____ |
Troposphere |
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The temperature decrease with increasing height in the troposphere is called the ____________ |
Environmental lapse rate |
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The average value of the environmental lapse rate in the troposphere is ______ per 1000 feet. This figure is known as the ________. However, it's value is ______
|
3.5F, normal lapse rate, variable |
|
To determine the actual environmental lapse rate as well as gather information about vertical changes in pressure, wind, and humidity, ______ are used. |
radiosonde |
|
An instrument package that is attached to a balloon and transmits data by radio as it ascends through the atmosphere
|
radiosonde |
|
The thickness of the troposphere varies with __________ |
latitude and season |
|
The outer boundary of the troposphere is the ________ |
the tropopause. |
|
Beyond the tropopause is the __________
|
stratosphere |
|
In the stratosphere, the temperature remains constant to a height of about _______, and then then begins a gradual __________ that continues until the _______ |
12 miles, increase, stratopause, |
|
Below the tropopause, atmospheric properties such as temperature and humidity are readily transferred by _______________ |
large-scale turbulence and mixing. |
|
Temperatures increase in the stratosphere because __________ |
it is in this layer that the atmosphere’s ozone is concentrated |
|
The third layer of the atmosphere is called the ______ |
Mesosphere |
|
In the mesosphere temperatures ______ with height until the __________
|
decrease, mesopause |
|
The coldest temperatures anywhere in the atmosphere occur at the __________ |
mesopause. |
|
the ________ is one of the least explored regions of the atmosphere. |
mesosphere |
|
The fourth layer of the atmosphere is the _________ |
thermosphere |
|
In the thermosphere, temperatures ______ due to the absorption of _______
|
increase, very short-wave, high-energy solar radiation by atoms of oxygen and nitrogen. |
|
Temperatures rise to extremely high levels of more than _______ in the thermosphere |
1800f |
|
Temperature is defined in terms of ________ |
the average speed at which molecules move. |
|
The amount of solar energy the Earth receives depends on ____________ |
latitude, time of day, and season of the year |
|
It is the _________ of Earth that creates winds and drives the ocean’s currents. |
unequal heating |
|
Earth has two principal motions—its ______ about its axis and its ________ around the Sun. |
rotation, orbital motion |
|
The axis is an _________ running through the poles. |
imaginary line |
|
Our planet rotates on its axis once every _____ |
24 hours, |
|
The line separating the dark half of Earth from the lighted half is called the |
circle of illumination
|
|
When the Earth is at its closest to the sun, that is known as the _____ |
perihelion |
|
When the Earth is at its furthest from the sun, that is known as the _____ |
aphelion |
|
The distance from the Earth to the sun plays a _____ in producing seasonal temperature variations |
minor role
|
|
Earth's seasons are due to the ________ of the axis, which is tilted at _______ degrees |
Inclination, 23.5 |
|
On June 21 or 22, the vertical rays of the vertical rays of the sun strike a latitude known as _______ |
The Tropic of Cancer |
|
For people in the Northern Hemisphere, June 21 or 22 is known as the _________ |
summer solstice |
|
On about December 21 or 22, the Sun’s vertical rays strike ________ |
The Tropic of Capricorn |
|
For people in the Northern Hemisphere,December 21 or 22 is known as the _________ |
Winter solstice
|
|
Midway between the solstices are the |
equinoxes |
|
September 22 or 23 is the date of the |
Fall equinox |
|
In the Northern Hemisphere, and March 21 or 22 is the date of |
The spring equinox |
|
During the equinoxes , the vertical rays of the sun strike the _______ |
equator |
|
The length of daylight versus darkness is also determined by Earth’s_________ |
Position in orbit |
|
The farther north of the equator you are on June 21, the longer the _________ |
period of daylight |
|
Heat is a term that is commonly used synonymously with _______ |
thermal energy |
|
heat is energy possessed by a material arising from the _______ |
internal motions of its atoms or molecules |
|
Whenever a substance is heated, its atoms ________, which leads to an increase in its heat content. |
move faster and faster |
|
heat generally refers to the ______ of energy present, whereas the word temperature refers to the _______ |
quantity, intensity |
|
In all situations, heat is ____ from warmer to cooler objects. |
transferred |
|
The flow of energy can occur in three ways: ____ |
conduction, convection, and radiation |
|
True or false: all three mechanisms of heat transfer can operate simultaneously |
True |
|
The transfer of heat through matter by molecular activity. |
Conduction |
|
The transfer of heat by mass movement or circulation within a substance. |
Convection |
|
Convection takes place in ______ |
Fluids
|
|
most of the heat acquired in the lowest portion of the atmosphere by way of radiation and conduction is transferred upward by _____ |
Convection |
|
the global convective circulation of the atmosphere is driven by _____ |
the unequal heating of Earth’s surface. |
|
Unlike conduction and convection, which need a medium to travel through, ________ energy readily travels through the vacuum of space |
radiant |
|
________ travels out in all directions from its source. |
radiation |
|
All radiation, whether x-rays, radio waves, or heat waves, travels through the vacuum of space at ______ |
186k miles per second
|
|
______ cannot be seen, but can be detected as heat. |
infrared radiation, |
|
When any form of radiant energy is absorbed by an object, the result is __________, which causes a corresponding increase in temperature. |
an increase in molecular motion |
|
True/False: All objects, at whatever temperature, emit radiant energy.
|
True |
|
True/False: Hotter objects radiate more total energy per unit area than do colder objects |
True |
|
True/False: Hotter objects radiate more energy in the form of short-wavelength radiation than do cooler objects |
True |
|
True/False: Objects that are good absorbers of radiation are good emitters as well. |
True |
|
When radiation strikes an object, ___ different results usually occur. 1. some of the energy is ______ by the object 2. Substances such as water and air are transparent to certain wavelengths of radiation. Such materials simply _____ this energy 3 some radiation may _____ the object without being absorbed or transmitted. This is known as ________ and/or ______ |
three absorbed transmit “bounce off” , reflection, scattering |
|
_________ and ________ are responsible for redirecting incoming solar radiation. |
Reflection, scattering |
|
On average, about _______ percent of the solar energy that reaches the top of the atmosphere is absorbed at Earth’s surface. Another ______ percent is reflected back to space by the atmosphere, clouds, and reflective surfaces. The remaining _____ percent is absorbed by clouds and the atmosphere’s gases. |
50 30 20 |
|
What determines whether solar radiation will be transmitted to the surface, scattered, reflected outward, or absorbed by the atmosphere? |
wavelength of the energy being transmitted, as well as on the nature of the intervening material. |
|
The process whereby light bounces back from an object at the same angle at which it encounters a surface and with the same intensity. |
Reflection |
|
A general process in which radiation is forced to deviate from a straight trajectory. |
Scattering |
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Whether solar radiation is reflected or scattered depends largely on the size of __________ |
The intervening particles and the wavelength of the light. |
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Energy is returned to space from Earth in two ways: ______ |
reflection and emission of radiant energy. |
|
The portion of solar energy that is reflected back to space leaves in the same ________ in which it came to Earth. |
short wavelengths |
|
The fraction of the total radiation that is reflected by a surface is called its _______ |
albedo |
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albedo varies considerably both from place to place and from one time to another, depending on the amount of ______ and particulate matter in the air, on the angle of the Sun’s rays, and on the nature of the ________ |
cloud cover, surface
|
|
Although incoming solar radiation travels in a straight line, small dust particles and gas molecules in the atmosphere scatter some of this energy in all directions. The result is called ____ |
diffused light |
|
_______ explains how light reaches into the area beneath a shade tree and how a room is lit in the absence of direct sunlight |
diffused light |
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_______accounts for the brightness and even the blue color of the daytime sky |
scattering |
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Overall, ________ of the solar radiation that is absorbed at Earth’s surface arrives as diffused (scattered) light. |
about half |
|
Because gases are ______, they absorb some wavelengths strongly, some moderately, and some only slightly. |
selective absorbers |
|
True/false: Nitrogen, the most abundant constituent in the atmosphere, is a poor absorber of all types of incoming solar radiation. |
True |
|
______ along with oxygen and ozone, accounts for most of the solar radiation absorbed directly by the atmosphere. |
Water vapor |
|
For the atmosphere as a whole, none of the gases are effective absorbers of ____ |
visible radiation. |
|
Because Earth has a much lower surface temperature than the Sun, the radiation that it emits has ________ than solar radiation. |
longer wavelengths |
|
_________absorbs roughly five times more terrestrial radiation than do all the other gases combined and accounts for the warm temperatures found in the ________ |
Water vapor, lower troposphere |
|
What explains the general drop in temperature with increasing altitude experienced in the troposphere? |
The atmosphere is heated from the ground up rather than vice versa. |
|
An______ is a line that connects points on a map that have the same temperature |
isotherm |
|
all points through which an isotherm passes have identical temperatures for _________ |
the time period indicated. |
|
A _________ is any factor that causes temperature to vary from place to place and from time to time. |
temperature control |
|
The most important cause for temperature variations is the |
differences in the receipt of solar radiation based on latitude. |
|
Temperature controls include: differential ______ of land and water, ________, geographic position, cloud cover and albedo, and ______ |
heating, altitude, ocean currents |
|
_________ temperatures are much higher than water-surface temperatures |
Land-surface |
|
True/False: land heats more rapidly and to higher temperatures than water |
True |
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True/False: Land cools more rapidly and to lower temperatures than water. |
True |
|
Variations in air temperatures are much greater over______ than over _________ |
land, water |
|
The amount of energy needed to raise the temperature of 1 gram of a substance 1°C is called the _____ |
specific heat |
|
Since land surfaces are ________, heat is absorbed only at the surface. Water, being more ______, allows heat to penetrate to a depth of many meters |
opaque, transparent |
|
Because the Southern hemisphere contains more ______ annual temperature variations are smaller than in the Northern Hemisphere |
Water
|
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The fact that high-altitude places are warmer than the value calculated using the normal lapse rate results from the ________ of solar energy by the ground surface. |
absorption and reradiation |
|
A coastal location where prevailing winds blow from the ocean onto the shore is called a ______ |
windward coast |
|
a coastal location where the prevailing winds blow from the land toward the ocean is called ____ |
a leeward coast |
|
A _____ coast will experience the full moderating influence of the ocean—cool summers and mild winters—compared to an inland station at the same latitude. |
windward |
|
A ______coast, on the other hand, will have a more continental temperature pattern because the winds do not carry the ocean’s influence onshore. |
leeward |
|
at any particular time, about _____ of our planet is covered by clouds |
half |
|
Cloud cover is important because many clouds have a high _____ |
albedo |
|
At night, clouds have the _______ as during daylight |
opposite effect |
|
The effect of cloud cover is to reduce the daily temperature range by lowering the _____ maximum and raising the ______ minimum |
daytime, nighttime |
|
______ is composed of water molecules that form a tight, orderly network held together by mutual molecular attractions |
Ice |
|
In the ______ state, water molecules are still tightly packed but are moving fast enough that they are able to slide past one another. |
liquid |
|
________ molecules are widely spaced compared to liquid water and exhibit ________ motion. |
Water-vapor, energetic random |
|
One _______ is the amount of heat required to raise the temperature of 1 gram of liquid water 1°C |
calorie |
|
Because the heat used to melt ice does not produce a temperature change, it is referred to as ________ |
latent heat |
|
Heat is absorbed during ______, the process of converting a liquid to a gas |
evaporation |
|
During the process of evaporation, the higher-temperature (faster-moving) molecules escape the surface. As a result, the average molecular motion (temperature) of the remaining water is ______ |
reduced |
|
_______, occurs when water vapor changes to the liquid state |
condensation |
|
During _________, water-vapor molecules release energy in an amount equivalent to what was absorbed during _____________ |
condensation, evaporation. |
|
When water vapor condenses to form cloud droplets, latent heat of condensation is released, warming the surrounding air and giving it _________ |
buoyancy. |
|
The conversion of a solid directly to a gas, without passing through the liquid state. |
Sublimation |
|
The conversion of a vapor directly to a solid. These deposits are called _____ |
Deposition, frost |
|
Sscientists agree that _________ is the most important gas in the atmosphere when it comes to understanding atmospheric processes. |
water vapor |
|
The maximum quantity of water vapor that the air can hold at any given temperature and pressure.Savanna |
Saturation |
|
The total atmospheric pressure that can be attributed to the water-vapor content. |
Vapor-pressure |
|
At higher temperatures, more moisture is required to reach _________ |
saturation |
|
The ____________ is the mass of water vapor in a unit of air compared to the remaining mass of dry air: |
mixing ratio |
|
The ratio of the air’s actual water-vapor content to the amount of water vapor required for saturation at that temperature (and pressure). |
Relative humidity |
|
When the water-vapor content of air remains at a constant level, a decrease in air temperature results in ______ in relative humidity, and an increase in temperature causes _____ in relative humidity. |
an increase , a decrease |
|
The temperature at which water vapor begins to condense |
Dew point |
|
Because the dew point is the temperature at which saturation occurs, we can conclude that ______ temperatures indicate moist air and, conversely, _______ temperatures indicate dry air |
high dew-point, low dew-point |
|
Humidity is measured with instruments called ____ |
hygrometers |
|
A type of hygrometers, known as a _____ consists of two identical thermometers mounted side by side |
psychometer
|
|
Electric Hygrometers operate on the principle of ________, a material’s ability to store an electrical charge.
|
capacitance |
|
Temperature changes in which heat energy is neither added nor subtracted, are called ___________ Instead, the change in temperature is caused by a change in ________ |
adiabatic temperature changes, pressure |
|
When air is compressed, it ___ and when air is allowed to expand, it ________ |
warms, cools. |
|
Unsaturated air cools at a constant rate of ____ for every 1000 meters of ascent. Conversely, descending air comes under increasing pressure and is compressed and heated by _____ for every 1000 meters of descent This rate of cooling or heating applies only to unsaturated air and is known as the ________ |
10C 10°C dry adiabatic rate |
|
If an air parcel rises high enough, it will eventually cool to its dew point, triggering the process of ________ |
condensation. |
|
The altitude at which a parcel reaches saturation and begins to form clouds is called the _______ |
condensation level |
|
At the lifting condensation level, an important change occurs: The ______ that was absorbed by the water vapor when it evaporated is released as ________—energy that can be measured with a thermometer. |
latent heat, sensible heat |
|
Although an air parcel will continue to cool adiabatically as it rises, the release of latent heat slows the rate of cooling. In other words, when a parcel of air ascends above the lifting condensation level, the rate at which it cools is reduced. This slower rate of cooling is called the ________ |
wet adiabatic rate |
|
Rising air expands and cools at the ________ rate from the surface up to the lifting condensation level, after which it cools at the slower ________ rate. |
dry adiabatic, wet adiabatic |
|
The type of lifting where air is forced to rise over a mountainous barrier |
Orographic lifting |
|
The type of lifting in which warmer, less-dense air is forced over cooler, denser air |
Frontal lifting |
|
When there's a pileup of horizontal airflow that results in upward movement it is called ___ |
convergence |
|
The type of lifting in which unequal surface heating causes localized pockets of air to rise because of their buoyancy is called ______ |
Localized convective lifting
|
|
As air ascends a mountain slope, ______ cooling often generates clouds and copious precipitation. |
adiabatic |
|
Many of the rainiest places in the world are located on ________ |
Windward mountain slopes. |
|
By the time air reaches the ______ side of a mountain, much of its moisture has been lost. If the air ________, it warms adiabatically, making condensation and precipitation even less likely. |
leeward, descends |
|
In central North America, warm and cold air masses often collide, producing boundaries called _________ Rather than mixing, the _______, denser air mass acts as a barrier over which the ________, less-dense air rises. |
fronts cooler, warmer |
|
When the wind pattern near Earth’s surface is such that more air is entering an area than is leaving—a phenomenon called ______ |
convergence |
|
When air is compressed by _______, it escapes by moving upward. |
convergence |
|
________ can occur when an obstacle slows or restricts horizontal airflow (wind). For example, when air moves from a relatively smooth surface, such as the ocean, onto an irregular landscape, increased friction reduces its speed. |
Convergence |
|
On warm summer days, unequal heating of Earth’s surface may cause some pockets of air to be warmed more than the surrounding air. Consequently, the overlying parcel of air, being warmer (less dense) than the surrounding air, will be buoyed upward. Such rising parcels of warmer air are called ______ |
thermals. |
|
The phenomenon that produces rising thermals is called ___________ |
localized convective lifting |
|
Air that is ____ (and hence denser) than the surrounding air, will sink back down to its original location. Air of this type, is called ______ |
cooler, stable air
|
|
Air that is _______ than the surrounding air (and hence less dense), it will continue to rise. Specifically, it will rise until it reaches an altitude where its temperature equals that of its surroundings. This type of air is called _______ |
warmer, unstable air |
|
_________ prevails when the environmental lapse rate is less than the wet adiabatic rate. |
Absolute stability |
|
The most stable conditions occur when the temperature in a layer of air actually increases with altitude rather than decreases. When such a reversal occurs, a ___________ is said to exist. |
temperature inversion |
|
Air is said to exhibit ______ when the environmental lapse rate is greater than the ______________ |
absolute instability, dry adiabatic rate. |
|
_________occurs when moist air has an environmental lapse rate between the dry and wet adiabatic rates |
conditional instability |
|
conditional instability depends on whether the rising air is __________ |
conditional instability |
|
A column of air is deemed ________ when the air near the bottom of the column is significantly warmer (less dense) than the air aloft, indicating a steep _______________ |
unstable, environmental lapse rate |
|
An air column is considered to be _______ when the temperature drops relatively slowly with increasing altitude. |
stable |
|
The most stable air conditions occur during a ___________, when the temperature actually _____________ with height. |
temperature inversion, increased |
|
When stable air is forced aloft, the clouds that form are widespread and have little vertical thickness when compared to their horizontal dimension, and precipitation, if any, is _________ |
light to moderate. |
|
True/False: Clouds associated with the lifting of unstable air are towering and often generate thunderstorms and occasionally even tornadoes |
True |
|
on a dreary, overcast day with light drizzle, _______ air has been forced aloft |
stable |
|
during a day when cauliflower-shaped clouds appear to be growing as if bubbles of hot air are surging upward, we can be fairly certain that the ascending air is ________ |
unstable |
|
When condensation occurs high above the ground, tiny bits of particulate matter, known as ________, serve as surfaces for water-vapor condensation |
cloud condensation nuclei |
|
A form of condensation best described as visible aggregates of minute droplets of water or tiny crystals of ice. |
Clouds |
|
louds are classified on the basis of two criteria: ________ |
form and height |
|
______ clouds are high, white, and thin. |
Cirrus |
|
_____ clouds consist of sheets or layers that cover much or all of the sky. |
Stratus |
|
______ clouds consist of globular cloud masses that are often described as cottonlike in appearance |
Cumulus |
|
the term ______ is added to the name of a cloud that is a major producer of precipitation. |
nimbus |
|
In terms of their height, clouds are classified as ______, ________, _______, and clouds of vertical development |
high, middle, low |
|
Because of the low temperatures and small quantities of water vapor present at high altitudes, all high clouds are _______ and are made up of __________ |
thin and white, ice crystals. |
|
Clouds that appear in the middle range have the prefix ____ as part of their name |
alto |
|
clouds of __________ tend to be associated with unstable air, which rises because of its buoyancy |
vertical development |
|
A cloud with its base at or very near the ground. |
fog |
|
fog occurs because air either is ______ its dew-point temperature or gains water through ________ until it becomes saturated |
cooled below, evaporation |
|
________ results when ground cooled by radiation cools the overlying layer of air. |
Radiation fog |
|
When warm, moist air blows over a cold surface, it becomes chilled by contact with the cold surface below. If cooling is sufficient, the result is a blanket of fog called ________ |
advection fog |
|
When relatively humid air moves up a gradually sloping landform or, in some cases, up the steep slopes of a mountain _____ can form |
upslope fog |
|
When air forms fog mainly because of the addition of water vapor, the fog is called an ________ |
evaporation fog. |
|
When cool, unsaturated air moves over a warm water body, enough moisture may evaporate to saturate the air directly above, generating a layer of fog called ________ |
steam fog |
|
Frontal boundaries where a warm, moist air mass is forced to rise over cooler, dryer air below generate___________ fog |
frontal |
|
fog incidence is highest in ______ areas, especially where ______ currents prevail |
coastal, cold
|
|
The __________ process generates much of the precipitation that occurs in the middle and high latitudes. |
Bergeron |
|
The Bergeron process is based on the fact that cloud droplets remain liquid at temperatures as low as ______ |
−40°C |
|
Liquid water at temperatures below freezing is termed _______ |
supercooled |
|
Supercooled water droplets also freeze upon contact with particles in the atmosphere known as ________ |
ice nuclei |
|
The _________ process involves multiple collisions of tiny cloud droplets that stick together to form raindrops large enough to reach the ground before evaporating. |
collision–coalescence |
|
Freezing rain forms when the cold layer of air is not deep enough to refreeze the raindrops, resulting in _________ droplets freezing on contact with objects at the surface. |
supercooled |
|
Snowfall is typically measured by _____ and ____ equivalent. |
depth, water |
|
_____ is the pressure exerted by the weight of air above. |
air pressure |
|
air pressure is exerted in all _________ |
directions |
|
When meteorologists measure atmospheric pressure, it is expressed in units called ________ |
millibars. |
|
Although the millibar has been the unit of measure on all U.S. weather maps since January 1940, the media use _______ |
inches of mercury |
|
An _________ uses a partially evacuated metal chamber to measure air pressure |
aneroid barometer |
|
Do Barometric readings always indicate the weather? |
No |
|
To “predict” the local weather, the _____________ is more important than the current pressure reading. |
change in air pressure over the past few hours |
|
_______ pressure is often associated with increasing cloudiness and the possibility of precipitation, whereas ______ air pressure generally indicates clearing conditions. |
Falling, rising |
|
a _________, provides a continuous record of pressure changes with the passage of time |
barograph |
|
What causes wind? |
Wind is the result of horizontal differences in air pressure. Air flows from areas of higher pressure to areas of lower pressure |
|
__________ is the ultimate energy source for most wind |
solar radiation |
|
The __________ of Earth’s surface generates the pressure differences that cause wind |
unequal heating |
|
If Earth did not rotate, and if there were no friction between moving air and Earth’s surface, air would flow in a ________ from areas of higher pressure to areas of lower pressure. |
straight line |
|
Wind is controlled by a combination of three factors: _____________ |
pressure gradient force, Coriolis effect, and friction. |
|
_________ cause the wind to blow, and the greater these differences, the greater the _________ |
pressure differences, wind speed. |
|
pressure measurements are shown on surface weather maps using ________ |
isobars |
|
The spacing of ________ indicates the amount of pressure change occurring over a given distance, which is called the _________ |
isobars, pressure gradient force |
|
Pressure gradient is analogous to ________ acting on a ball rolling down a hill |
gravity |
|
Closely spaced isobars indicate ____________and strong winds; widely spaced isobars indicate ______________ and light winds. |
a steep pressure gradient, a weak pressure gradient |
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the __________ gradient is the driving force of wind. |
horizontal pressure
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Wind does not cross isobars at right angles, as the pressure gradient force directs it to do. The direction deviates as a result of Earth’s rotation. This has been named the ________ |
Coriolis effect |
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All free-moving objects or fluids, including the wind, are deflected to the ______ of their path of motion in the Northern Hemisphere and to the ______ in the Southern Hemisphere. |
right, left |
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The Coriolis effect is always directed at _____ to the direction of airflow; affects only _________, not wind speed; is affected by wind speed (the stronger the wind, the ______ the deflection); and (4) is strongest at the ______ and weakens ____________, becoming nonexistent at the __________ |
right angles, wind direction, greater, poles, equatorward, equator. |
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The effect of ______ on wind is important only within a few kilometers of Earth’s surface |
friction |
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Upper air winds are called ________
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geostrophic winds |
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The lack of ______ with Earth’s surface allows __________ to travel at higher speeds than do surface winds. |
friction, geostrophic winds |
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The most prominent features of upper-level air flow are _______ |
jet streams |
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Friction lowers the _______ so it reduces the Coriolis effect. |
wind speed, |
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_______, or lows, are centers of low pressure, and ________ or highs, are high-pressure centers. |
Cyclones, anticyclones, |
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When the controls of airflow are applied to pressure centers in the Northern Hemisphere, the result is that winds blow ______ and counterclockwise around a low. Around a high, they blow _________ and _________ |
inward, counterclockwise, outward, clockwise |
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In the Southern Hemisphere, the Coriolis effect deflects the winds to the _____; therefore, winds around a low blow ______, and winds around a high move ________ |
left, clockwise, counterclockwise |
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In either hemisphere, friction causes a net inflow ______ around a cyclone and a net outflow _________ around an anticyclone. |
convergence, divergence |
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In a surface low-pressure system where the air is spiraling inward. The net inward transport of air causes a shrinking of the area occupied by the air mass, a process that is termed ________ |
horizontal convergence. |
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Whenever air converges ________, it must pile up—that is, increase in height to allow for the decreased area it now occupies |
horizontally |
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A low, or cyclone, has________ surface winds and _______ air, resulting in cloudy conditions. A high, or anticyclone, has ______ surface winds and________ air, which leads to clear skies and fair weather. |
converging, rising, diverging, descending |
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The atmosphere acts as a giant heat-transfer system, moving ______ poleward and _______ equatorward |
warm air, cool air |
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Near the equator, the rising air is associated with the pressure zone known as the __________. Because this region of low pressure is a zone where winds from the north and south converge, it is also referred to as the ____________ |
equatorial low intertropical convergence zone |
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As the diverging upper-level flow from the equatorial low reaches 20° to 30° latitude, north or south, it sinks back toward the surface. This subsidence and associated adiabatic heating produce hot, arid conditions. The center of this zone of subsiding dry air is the ________, which encircles the globe near 30° latitude, north and south. |
subtropical high |
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At the surface, airflow is outward from the center of the subtropical high. Some of the air travels equatorward and is deflected by the Coriolis effect, producing the _________ The remainder travels poleward and is also deflected, generating the _________ As the westerlies move poleward, they encounter the cool _______in the region of the ________. The interaction of these warm and cool winds produces the stormy belt known as the ________ |
trade winds westerlies polar easterlies, subpolar low, polar front |
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The source region for the variable polar easterlies is the ________ |
polar high |
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The subtropical and polar highs are areas of dry subsiding air that flows ______at the surface, producing the ________ |
outward, prevailing winds. |
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The low-pressure zones of the equatorial and subpolar regions are associated with _____ and _________ airflow accompanied by clouds and precipitation. |
inward, upward |
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The only truly continuous pressure belt is the _______in the Southern Hemisphere, where the ocean is ___________ by landmasses |
subpolar low, uninterrupted |
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large landmasses, become cold in the winter and develop a seasonal ________ system from which surface flow is directed _____ the land. In the summer, the opposite occurs: The landmasses are heated and develop a _______, which permits air to flow ______ the land. These seasonal changes in wind direction are known as the __________ |
high-pressure, off low-pressure cell, onto, monsoons |
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Because the paths of low-pressure centers are guided by the flow aloft, we can expect the ________ of states to experience more of their stormy weather in the winter season. During the hot summer months, the storm track is across the ________ |
southern tier, northern states. |
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________ are small-scale winds produced by a locally generated pressure gradient. |
Local winds |
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In coastal areas during the warm summer months, the land is heated more intensely during the daylight hours than is the adjacent body of water. As a result, the air above the land surface heats, expands, and rises, creating an area of ________ A ______ then develops because cooler, _______ air over the water moves toward the warmer, _________air over the land At night, the reverse may take place: The land cools more rapidly than the sea, and the _______ develops |
lower pressure, sea breeze , higher pressure, lower pressure Land Breeze |
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During daylight hours, the air along the slopes of the mountains is heated more intensely than the air at the same elevation over the valley floor. Because this warmer air is less dense, it glides up along the slope and generates a _________ |
valley breeze |
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Rapid radiation cooling along the mountain slopes produces a layer of cooler air next to the ground. Because cool air is denser than warm air, it drains downslope into the valley. This movement of air is called a _________ |
mountain breeze |
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Warm, dry winds sometimes move down the eastern slopes of the Rockies, where they are called ___________________. the winds occur mostly in the ___________ |
Chinooks winter and spring |
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Two basic wind measurements, __________, are particularly significant to weather observers. |
direction and speed |
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Winds are always labeled by the _____________ |
direction from which they blow |
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The instrument most commonly used to determine wind direction is the __________ |
wind vane |
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Wind speed is commonly measured using a _________ |
cup anemometer |
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When the wind consistently blows more often from one direction than from any other, it is called a ____________ |
prevailing wind |
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During an __________, strong equatorial countercurrents amass large quantities of warmer-than-normal water along the west coast of South America. The unusually warm water and associated low pressure cause arid areas of Peru and Chile to receive ____________ that can lead to___________ |
El Niño, unusually heavy rains, major flooding. |
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During an El Niño event, the pressure over the eastern Pacific _______, while the pressure over the western Pacific ______ This causes the trade winds to _________, leading to an __________ movement of warm water along the equator. |
drops, rises. diminish, eastward |
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During a ______ event, strong trade winds drive the equatorial currents toward the west. This circulation pattern is often associated with flooding in _________ whereas especially dry conditions prevail along the west coast of South America. |
La Niña, northeastern Australia and Indonesia, |
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During an ______ event, winter temperatures are warmer than normal in the north-central United States and parts of Canada In addition, significantly ____ winters are experienced in the southwestern United States and northwestern Mexico, while the southeastern United States experiences _______ and cooler conditions. |
El Niño wetter, wetter |
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One major benefit of El Niño is a lower-than-average number of ___________ |
Atlantic hurricanes. |
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La Niña winter weather includes _______ conditions over the northwestern United States and especially _______ winter temperatures in the Northern Plains states, while _______ conditions occur in the Southwest and Southeast |
cooler and wetter, cold, unusually warm |
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El Niño and La Niña events are intimately related to changes in the global _______ patterns. |
pressure |
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Each time an El Niño occurs, the barometric pressure _______ over large portions of the eastern Pacific and ________ in the tropical portions of the western Pacific. |
drops, rises |
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The seesaw pattern of atmospheric pressure between the eastern and western Pacific is called the ____________ |
Southern Oscillation |
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_______ in the western Pacific strengthens the trade winds, which move warm, tropical water toward Australia and Indonesia |
Low pressure |
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A _______ in pressure in the eastern Pacific weakens the trade winds and strengthens the _________, which amass large quantities of warm water along the coasts of Peru and Chile. |
drop, equatorial countercurrents |
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The link between the weather occurring in widely separated regions of the globe is called a _______ |
teleconnection. |
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National Weather Service predictions for periods from 1 to 13 months into the future are called ________ |
climate outlooks. |
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In general, regions influenced by high pressure, with its associated subsidence and diverging winds, experience relatively ________ |
dry conditions |
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Regions under the influence of low pressure and its converging winds and ascending air receive _______ |
Ample precipitation |
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Large landmasses in the middle latitudes commonly experience ______ precipitation toward their interiors. |
decreased |
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An _______, is an immense body of air, usually 1,600 kilometers (1,000 miles) or more across and perhaps several kilometers thick, that is characterized by a similarity of temperature and moisture across a given altitude. |
air mass |
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Since it may take several days for an air mass to move across an area and be modified, the region under its influence will likely experience fairly constant weather, a situation called _______ |
air-mass weather |
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The area where an air mass acquires its characteristic properties of temperature and moisture is called its _________ |
source region |
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Air masses are classified according to their ______ _______ air masses and ________ air masses originate in high latitudes toward Earth’s poles, whereas those that form in low latitudes are called _________ air masses In addition, air masses are classified according to the nature of the surface in the source region. ________ air masses form over land, and _______ air masses originate over water. |
Source region. Polar (P), arctic, tropical (T) Continental, maritime (m) |
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The basic types of air masses are _________ |
continental polar (cP), continental arctic (cA), continental tropical (cT), maritime polar (mP), and maritime tropical (mT). |
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_________ masses influence the weather of North America most, especially east of the ________ Continental polar air masses originate in ___________ |
Continental polar and maritime tropical air, Rocky Mountains. northern Canada, interior Alaska, and the Arctic |
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Although cP air masses are not, as a rule, associated with heavy precipitation, those that cross the ___________ during late autumn and winter sometimes bring snow to the leeward shores. These localized storms often form when the surface weather map indicates no apparent cause for a snowstorm. These are known as________ |
Great Lakes lake-effect snows |
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Maritime tropical air masses affecting North America most often originate over the warm waters of the ___________________ |
Gulf of Mexico, the Caribbean Sea, or the adjacent Atlantic Ocean |
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______ air is the source of much, if not most, of the precipitation in the eastern two-thirds of the United States. |
Maritime tropical |
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During the winter, maritime polar air masses coming from the North Pacific often originate as ________ air masses in ____________ |
continental polar, Siberia. |
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______ are boundary surfaces that separate air masses of different densities—one of which is usually warmer and contains more moisture than the other. |
Fronts |
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The process of warm air gliding up and over a cold air mass is termed _________ |
overrunning |
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When the surface position of a front moves so that warm air occupies territory formerly covered by cooler air, it is called a _________ |
warm front |
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When dense cold air is actively advancing into a region occupied by warmer air, the boundary is called a _______ |
cold front |
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On average, cold fronts are about _____ as steep as warm fronts, |
twice |
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Occasionally, the flow on both sides of a front is neither toward the cold air mass nor toward the warm air mass but almost parallel to the line of the front. Thus, the surface position of the front does not move. This condition is called a ______ |
stationary front |
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An active cold front that overtakes a warm front is called a |
occluded front
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Middle latitudes refers to the region between _________. The primary weather producers here are _______ |
southern Florida and Alaska middle-latitude, cyclones |
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________ cyclones are large centers of low pressure that generally travel from west to east. Lasting from a few days to more than a week, these weather systems have a __________ circulation, with an airflow inward toward their centers. |
Midlatitude, counterclockwise |
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With respect to surface cyclones , as long as _________ aloft is equal to or greater than surface inflow, the low pressure and its accompanying ______ can be sustained.
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divergence, convergence |
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The surface air that feeds a cyclone, generally originates as air flowing out of _______ |
an anticyclone. |
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Tornadoes and hurricanes are both _________ than midlatitude cyclones |
smaller and more violent |
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The greatest number of thunderstorms occur in the ________ |
tropics |
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Pressures within some tornadoes have been estimated to be as much as ________ lower than pressures immediately outside the tornado. |
10 percent |
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Usually the most intense tornadoes are those that form in association with huge thunderstorms called ___________ |
supercells |
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___________ is a vertical cylinder of rotating air, typically about 3 to 10 kilometers (2 to 6 miles) across, that develops in the updraft of a severe thunderstorm. The formation of this large vortex often precedes tornado formation by 30 minutes or so. |
A mesocyclone |
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________ is a change in wind speed and/or direction with height |
Wind shear |
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Mesocyclone formation depends on the presence of ____________ |
wind shear |
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___________ of all mesocyclones produce tornadoes. |
half |
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Supercell thunderstorms are likeliest to form during the ______, when the air masses associated with midlatitude cyclones are most likely to have greatly contrasting conditions. The two contrasting air masses are most likely to meet in the central United States because there is no ______________ |
spring significant natural barrier |
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The commonly used guide to tornado intensity is the ___________________ |
Enhanced Fujita intensity scale, or EF-scale |
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The EF-scale is determined by assessing the ________ produced by a storm. |
worst damage |
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_________ alert the public to the possibility of tornadoes over a specified area for a particular time interval |
Tornado watches |
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A ______ is issued by local offices of the NWS when a tornado has actually been sighted in an area or is indicated by weather radar. |
A tornado warning |
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__________ are intense centers of low pressure that form over tropical oceans and are characterized by intense convective activity and strong cyclonic circulation |
Hurricanes |
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The source of energy that produces and maintains hurricane-force winds is the huge quantity of _______ liberated during the formation of the storm’s cumulonimbus towers. |
latent heat |
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In the western Pacific, hurricanes are called _____ |
typhoons |
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Hurricanes develop most often in the late _____, when ocean waters have reached temperatures of 27°C (80°F) or higher and thus are able to provide the necessary _______ to the air |
summer, heat and moisture |
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Hurricanes diminish in intensity whenever they _______ |
(1) move over ocean waters that cannot supply warm, moist tropical air; (2) move onto land; or (3) reach a location where the large-scale flow aloft is unfavorable. |
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Hurricanes are measured using the _________
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the Saffir–Simpson hurricane scale |
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Damage caused by hurricanes can be divided into three categories: _____ |
1) storm surge, (2) wind damage, and (3) heavy rains and inland flooding. |
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With respect to hurricanes, the most devastating damage in the coastal zone is usually caused by _____ |
storm surge |
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The predicted path of a hurricane is called the _______ |
track forecast. |
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The Earth's climate system includes: |
the atmosphere, hydrosphere, geosphere, biosphere, and cryosphere. |
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The _________ refers to the portion of Earth’s surface where water is in solid form |
cryosphere |
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The______ Classification is used for climates |
Koppen |
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The 5 principal groups under the Koppen classification system are |
Humid tropical (A)
Dry (B) Humid-middle lattitude, mild winters (C) Humid-Middle Latitude, severe winters (D) Polar (E) |
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Within the A group of climates, two main types are recognized: _________ |
wet tropical climates (Af and Am) and tropical wet and dry (Aw). |
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In the latitude zone poleward of the wet tropics and equatorward of the subtropical deserts lies the transitional _____________ |
tropical wet and dry climate |
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Climatologists define a dry climate as one in which the __________ is not as great as the potential loss of water by __________ |
yearly precipitation, evaporation |
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Unlike most other aerosols, _________ warms the atmosphere because it is an effective absorber of incoming solar radiation. |
black carbon |
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Climate feedback mechanisms that reinforce the initial change, are called __________ |
positive-feedback mechanisms |
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Climate feedback mechanisms that produce results the opposite of the initial change, are called __________ |
negative-feedback mechanism |