Exam 3 meteorology
What is considered standard sea-level atmospheric pressure in millibars?
1013.25mb
A station at an altitude of 900 m (about 3,000 feet) above sea level measures an air pressure of 930 mb. Under normal conditions, which of the values below do you think would be the most realistic sea level pressure for this station?
1020 mb
Suppose the wind speed increased from 5 mph to 10 mph. We can conclude that the force exerted by the wind increased by a factor of
4
The Coriolis force acts at a ____ degree angle to the wind.
90
A sea or land breeze is caused by
temperature differences
In the three-cell model of the atmosphere, upper level winds are incorrectly predicted to flow from ____.
the east
The size and shape of a turbulent eddy depends upon
the size and shape of the obstacle.
Wind gusts are caused by
turbulent eddies
There is always a strong pressure gradient force directed _________.
upward
While fly fishing in a mountain stream, you notice that the wind is blowing upstream. From this, you could deduce that the wind is a
valley breeze
What type of weather front would likely be responsible for the following weather forecast? "Increasing high cloudiness and cold this morning. Clouds increasing and lowering this afternoon with a chance of snow or rain tonight. Precipitation ending tomorrow morning. Turning much warmer. Winds light easterly today becoming southeasterly tonight and southwesterly tomorrow."
warm front
Chinook winds are
warm, dry downslope winds
Chinook winds are
warm, dry downslope winds
Compared to an mP air mass, mT air is
warmer and moister
The synoptic scale describes circulations on the ____ scale.
weather-map
An upper-level trough that shows retrograde motion would be moving toward the
west
For a surface storm system to intensify, the upper-level low (or trough) should be located to the ____ of the surface low.
west
Upper-level winds in the middle latitudes of both hemispheres generally blow from ____.
west
Atmospheric shortwaves usually move ____ at a speed that is ____ than longwaves.
west to east; faster
The majority of the United States lies within this wind belt
westerlies
Due to Hadley cell formation and the Coriolis force in both hemispheres, winds aloft flow
westerly
Due to Hadley cell formation and the Coriolis force in both hemispheres, winds aloft flow
westerly
Divergence and convergence of air are due to changes in
wind speed or wind direction
What is an example of mesoscale motion?
winds blowing through a city
Since the Northern Hemisphere's polar jet stream is strongest and moves farther south in ____, we can see why mid-latitude cyclonic storms are better developed and move more quickly during the ____ months.
winter; colder
The north-south temperature contrast along the polar front is strongest in ____ and weakest in ____.
winter; summer
In terms of the three-cell general circulation model, the driest regions of Earth should be near
30° latitude and the polar regions.
A geostrophic wind is a wind that results from a balance between the ____ force and the ____ force.
Coriolis; pressure gradient
The two ocean currents, warm and cold, that produce fog off the coast of Newfoundland are the
Gulf Streamand LabradorCurrent.
Which of the following statements is most plausible?
In winter, cA source regions have lower temperatures than cP source regions.
Which statement describes the polar front jet stream?
It forms near the boundary called the polar front.
In the Northern Hemisphere, the polar jet stream is strongest when
air north of the polar front is much colder than air south of the polar front.
If we assume that the absolute vorticity of flowing air is conserved, air moving northeastward will bend ____ to compensate for the ____ in Earth's vorticity.
anticyclonically; increase
On an upper-level chart where the isotherms cross the isobars (or contours) and temperature advection occurs, the atmosphere is called
baroclinic
In a mid-latitude cyclone, the warm sector is located
between the cold and warm fronts
On a weather map of the Northern Hemisphere, one would observe the westerlies
between the subpolar lows and the subtropical highs.
Another term for explosive cyclogenesis used by meteorologists is
bomb
A dryline is
both a dew point front and a boundary marking a strong horizontal change in atmospheric moisture.
Which air masses are formed in regions where long, clear nights allow for strong radiational cooling of the surface?
cP and cA
Which air mass would show the most dramatic change in both temperature and moisture content as it moves over a large body of very warm water?
cP in winter
In winter, which sequence of clouds would you most likely expect to observe as a warm front with precipitation approaches your location?
cirrus, cirrostratus, altostratus, and nimbostratus
The wind around a surface high pressure center in the Northern Hemisphere blows
clockwise and outward from the center.
On the eastern side of the Rocky Mountains, chinook winds are driest when
clouds form and precipitation falls on the upwind side of the mountains.
The piling up of air above a region is called
convergence
In a mid-latitude cyclone, an upper-level pool of cold air that has broken away from the main flow is called a
cut-off low
During the March, 1993 storm off the coast of Texas, a region of ____ air in the upper air above the storm caused the rapid decrease of surface pressure leading to the development of a wave cyclone.
diverging
Which region is considered to be a region where cyclogenesis often occurs?
eastern slopes of the Rocky Mountains
During a major El Niño event,
extensive ocean warming occurs over the tropical Pacific.
The wind's speed generally increases with height above Earth's surface because
friction with Earth's surface slows the air near the ground.
Meridional wind-flow patterns go
from either north-to-south or south-to-north.
A good source region for an air mass would be
generally flat areas of uniform composition with light surface winds.
The jet stream flows
in a wavy pattern from west to east.
A thermally direct cell is one that
is driven by energy from the Sun.
The air mass with the highest actual water vapor content is
mT.
The unit of pressure most commonly found on a surface weather map is
millibars or hectopascals.
Pressure changes
more rapidly in the vertical direction than in the horizontal.
The low-level jet that forms over the Central Plains of the United States in the summer appears to be responsible for
nighttime thunderstorms.
The world's deserts are found at 30° latitude because
of the sinking air of the subtropical highs.
A lee-side low forms
on the downwind side of a mountain
On an upper-level chart the wind tends to be
parallel to the isobars or contours.
In the three-cell model, the wind belt observed on the poleward side of the polar front is called the
polar easterlies.
The force that would cause a stationary parcel of air to begin to move horizontally is called the
pressure gradient force.
The amount of pressure change that occurs over a given horizontal distance is called the
pressure gradient.
During the winter as you travel toward a warm front, the most likely sequence of weather you would experience is
snow, sleet, freezing rain, and rain.
On a weather map of the Northern Hemisphere, the trade winds would be observed
south of the subtropical highs.
Generally, in the Northern Hemisphere during July, we would expect to find the tropical easterly jet stream
south of the upper-level subtropical high.
Lee-side lows are
storms (extratropical cyclones) that form on the eastern (lee) side of a mountain range
An air mass is characterized by similar properties of ____ and ____ in any horizontal direction.
temperature; humidity
Northeasters (or nor'easters) are midlatitude storms commonly found along
the Atlantic coast of North America
The ultimate cause of jet streams is
the energy imbalance between high and low latitudes.
In terms of the three-cell model of the general circulation, areas of surface low pressure should be found at
the equator and 60° latitude.
A wind rose indicates
the percentage of time that the wind blows from different directions.
upwelling is
the rising of cold water from below.
When an upper-level low lies directly above a surface low,
the surface low will probably weaken
When an upper-level low lies directly above a surface low,
the surface low will probably weaken
The Ekman Spiral describes
the turning of water with depth.
If huge waves pound against the beach communities of Southern California for several days during clear, calm weather, it is a good bet that
the winds are strong somewhere out over the Pacific Ocean.
Longwaves in the middle and upper troposphere usually have lengths on the order of
thousands of kilometers
The entrance region occurs ____ of a jet streak, while the exit region occurs ____ of the jet streak.
upwind; downwind
The entrance region occurs ____ of a jet streak, while the exit region occurs ____ of the jet streak. downwind; upwind
upwind; downwind
In a mid-latitude cyclone, when the upper low lies directly above the surface low, the storm system is said to be
vertically stacked
Divergence and convergence of air are due to changes in
wind speed or wind direction
Upwelling occurs along the northern California coast because
winds cause surface waters to move away from the coast.
A wind reported as 45°would be a wind blowing from the:
NE
What is a serious hazard to aircraft?
Clear Air Turbulence
The large thermally driven convection cell that is driven by convective "hot" towers along the equator is the
Hadley cell.
Which statement describes the subtropical jet stream?
It generally blows from west to east.
Which statement describes the subtropical jet stream?
It generally blows from west to east.
A condition where the central and eastern tropical Pacific Ocean turns cooler than normal is called
La Niña.
According to the three-cell general circulation model, at the equator we would not expect to find
a ridge of high pressure.
The development or strengthening of a middle latitude storm system is called
cyclogenesis
The development or strengthening of a middle latitude storm system is called
cyclogenesis
To correctly monitor horizontal changes in air pressure, the most important correction for a mercury barometer is the correction for
altitude
The pressure gradient force is directed from higher pressure toward lower pressure
at all places on earth
Which of the following instruments measures pressure?
barometer
On a surface weather map that shows an open wave cyclone, the warm sector can be observed
between the cold and warm fronts
The coldest of all air masses is
cA
Clear sunny days with very cold nights would be associated with what type of air mass?
cP
Record breaking low temperatures are associated with which air mass?
cP
What type of air mass would be responsible for refreshing cool, dry breezes after a long summer hot spell in the Central Plains?
cP
On a 500 millibar chart, ____ are drawn to represent horizontal changes in altitude which correspond to horizontal changes in pressure.
contour lines
Which of the following is associated with rising air motions in a mid-latitude cyclone?
convergence of air at the surface
Clouds and precipitation are frequently found on the downwind side of a large lake. This would indicate that the air on the downwind side is
converging and rising
Clouds and precipitation are frequently found on the downwind side of a large lake. This would indicate that the air on the downwind side is
converging and rising.
If upper-level divergence exceeds surface convergence, the air pressure at the center of the surface low will
decrease
The surface pressures at the bases of warm and cold columns of air are equal. Air pressure in the warm column of air will ____ with increasing height ____ in the cold column.
decrease; more slowly than
A front is the transition zone between two air masses of different
densities
Cyclogenesis is the ____ of a mid-latitude cyclone.
development or strengthening
As westerly winds blow over a north-south oriented mountain range, the airflow is deflected in such a way that a trough forms on the ____ side of the mountain.
downwind
Before the passage of a cold front the pressure normally ____, and after the passage of a cold front the pressure normally ____.
drops; rises
Thermal turbulence above the surface is usually most severe
during maximum surface heating.
At the equator, Earth rotates toward the east at a speed close to 1000 knots. On a windless day, the air above moves ____ at ____ speed.
eastward; the same
Which of the following produces the strongest Coriolis force?
fast winds; high latitude
Atmospheric shortwaves usually move ____ longwaves, and ____ when they move through a longwave ridge.
faster than; weaken
A true cold front on a weather map is always
followed by cooler air
Surface winds blow across isobars at an angle and the pressure gradient force is balanced by the ____ force and the Coriolis force.
frictional
An offshore wind blows
from land to water
The contour lines drawn on a 500 mb chart are lines of constant
height.
Horizontal pressure variations cause air to move from areas of _____ pressure to areas of ____ pressure.
high; low
Isobaric surfaces are ____ in warm, less-dense air and ____in cold, more-dense air.
higher; lower
The most practical location for building a wind turbine would be
in a region of moderate, steady winds.
During the summer along the coast, a sea breeze is usually strongest and best developed
in the afternoon
Surface winds are generally strongest and most gusty
in the afternoon
Thermally-generated eddies typically peak
in the afternoon
A pilot enters the weather service office and wants to know what time of the day she can expect to encounter the least turbulent winds at 760 m (2500 ft) above central Kansas. If you were the weather forecaster, what would you tell her?
in the early morning
If the flow of air into a surface low pressure area is greater than the divergence of air aloft, the surface pressure in the center of the low will
increase
As an air parcel aloft moves northward from the equator, it moves closer to Earth's axis of rotation. Because of the conservation of angular momentum, the air parcel's motion should
increase in speed
Net convergence of air would cause surface pressure to ____ and net divergence would cause surface pressure to ____.
increase; decrease
Wind blowing with sufficient force to rip the roof off buildings
is uncommon
During the summer in humid climates, nighttime clouds tend to form over water during a
land breeze
The nighttime counterpart of the sea breeze circulation is called
land breeze
Which of the below determines how high a wind wave will grow over the open ocean?
length of time the wind blows over the water
Rossby waves are also known as
longwaves
The designation for a cool, moist air mass is
mP
What type of air mass would be responsible for persistent cold, damp weather with drizzle along the east coast of North America?
mP
What type of air mass would be responsible for hot, muggy summer weather in the eastern half of the United States?
mT
The greatest contrast in both temperature and moisture will occur along the boundary separating which air masses?
mT and cP
Which name is given to a large cyclonic storm system that forms in the middle latitudes?
middle latitude cyclone
Pressure changes
more rapidly in the vertical direction than in the horizontal.
Because of friction, surface winds move ____ winds aloft with the same pressure gradient.
more slowly than
If you are standing directly south of a smoke stack and the wind from the stack is blowing over your head, what would be the wind direction?
north
A surface low pressure area with a deep upper-level trough to the west will tend to move toward the
northeast
The intertropical convergence zone (ITCZ) is a region where
northeast trades converge with the southeast trades.
The origin of cP and cA air masses that enter the United States is
northern Canada and Alaska
An upper wind direction is reported as 315°. From what compass direction is the wind blowing?
northwest
A sea breeze circulation will reverse direction and become a land breeze
once per day
The ____ jet is known to show seasonal variations. In winter, the winds are stronger and the jet moves farther south as the leading edge of the cold air can extend into subtropical regions, as far south as Florida and Mexico. In summer, the jet is weaker and is usually found over more northerly latitudes.
polar front
On an isobaric surface,
pressure is constant
At a warm front, the warm air
rises and cools
In middle latitudes, when an area of high pressure approaches a city, surface pressure usually ____. When it moves away, pressure usually ____.
rises; falls
Eddies that form both close to the mountain and beneath each wave crest are called
rotors
When a sea breeze moving east meets a sea breeze moving west, they form a
sea breeze convergence zone.
A small, moving disturbance imbedded in a longwave is called a
shortwave
In general and based on the three-cell model, along the polar front one would not expect to observe
sinking air aloft.
When a deep upper-level trough is located to the east of a surface anticyclone, the surface anticyclone will tend to move toward the
southeast
Vorticity refers to the
spin of air parcels
Alternating lines of blue and red on a surface weather chart indicate a(n)
stationary front
On a clear, windy day, the depth to which mixing occurs above the surface depends upon
surface heating
The ____ force is an apparent force created by Earth's rotation.
Coriolis
Occluded fronts may form when
a cold front overtakes a warm front
On a weather map, the transition zone between two air masses with sharply contrasting properties is marked by
a front.
One would expect a cP air mass to be
cold and dry
Squall lines most often form ahead of a
cold front
What type of weather front would likely be responsible for the following weather forecast? "Increasing cloudiness and warm today with the possibility of showers by this evening. Turning much colder tonight. Winds southwesterly becoming gusty and shifting to northwesterly by tonight."
cold front
In the Northern Hemisphere, air found to the north of the polar front is ____, while air further south is ____.
cold; warm
The heat from a chinook wind is generated mainly by
compressional heating.
A stationary front does not move because
the winds blow parallel to the front
The land/sea breeze, lake breeze, and mountain/valley breeze are examples of
thermal circulations
On a surface weather map during the month of July, one would expect to find what type of pressure system over the desert southwest of the United States?
thermal low