Deck 6: Air Pressure and Winds

Question 1

Why do surface winds cross the isobars at an angle toward lower pressure (instead of blowing parallel to the isobars)?

A) Friction reduces the speed so Coriolis is weakened.
B) It results from divergence in the surface wind.
C) Pressure gradient becomes stronger near the surface.
D) Convergence of upper level winds causes this.
E) Coriolis strengthens by combining with friction.

Answer 1

A

Question 2

When air moves from the ocean onto land:

A) curved flow is initiated.
B) converging winds and ascending air result over the land.
C) the winds tend to increase their speed.
D) divergence and subsidence occur over the land.

Answer 2

B

Question 3

Circulations in the earth's atmosphere are fundamentally caused by:

A) frontal storm systems.
B) gravity.
C) temperature contrasts between different locations.
D) ocean currents.
E) heating of the ozone layer.

Answer 3

C

Question 4

With respect to the Coriolis force, which association is NOT correct?

A) deflection - always at a 90 degree angle to the direction of air flow
B) North Pole - strongest deflection
C) Northern Hemisphere - deflection to the right of the wind's original direction
D) Low wind speeds - strongest deflection

Question 5

Anticyclonic flow is:

A) associated with air converging at the surface.
B) associated with low pressure.
C) in the opposite direction of Earth's rotation.
D) associated with storms and rainy conditions.

Question 6

Upper air winds:

A) are unaffected by the Coriolis force.
B) are greatly influenced by friction.
C) do not influence surface weather.
D) are generally faster than surface winds.

Question 7

A steep pressure gradient:

A) is only possible in the tropics.
B) produces light winds.
C) would be depicted by widely spaced isobars.
D) produces strong winds.

Question 8

If the earth were not rotating:

A) atmospheric pressure would decrease.
B) Earth would lose its atmosphere.
C) all winds would cease.
D) air would move directly from high to low pressure.

Question 9

Divergence in the atmosphere is best defined as:

A) clouds separating and dissipating.
B) air moving out of an area.
C) warm air moving away from cold air.
D) air piling up in one area.

Question 10

When geostrophic conditions exist in the atmosphere, the net force on the moving air is:

A) large since the wind speed is fast.
B) zero.
C) large when the wind speed is slow.
D) called a centrifugal force.
E) called a centripetal force.

Question 11

$\begin{array}{|c|c|}\hline \text { TIME } & \text { PRESSURE } \\\hline 10: 51 & 1016.2 \mathrm{mb} \\\hline 11: 51 & 1015.5 \mathrm{mb} \\\hline 12: 51 & 1015.0 \mathrm{mb} \\\hline 13: 51 & 1014.2 \mathrm{mb} \\\hline 14: 51 & 1013.9 \mathrm{mb} \\\hline 15: 51 & 1013.3 \mathrm{mb} \\\hline 16: 51 & 1013.0 \mathrm{mb} \\\hline\end{array}$ Consider the pressure data recorded at Albany International Airport on September 27, 2011. What statement can you make about the weather Albany is likely to experience soon?

A) Albany should have clearing skies.
B) Albany will definitely have a tornado within the hour.
C) Albany is likely to experience rain or storms soon.
D) Winds at Albany will likely be calming down.

Question 12

-Refer to the map above. Which of the following areas has the highest pressure gradient?

A) Southern Florida
B) Southwestern Texas
C) Lake Michigan/Southeastern Wisconsin
D) Southern California

Question 13

The geostrophic wind describes a situation where the air moves:

A) parallel to the isobars.
B) upward.
C) from pole to equator.
D) very slowly.

Question 14

It the Earth were not rotating:

A) all air would move in one direction only.
B) the Earth would lose its atmosphere.
C) friction would be eliminated.
D) winds would not be impacted by the Coriolis Effect.

Question 15

What units of pressure are used when air pressure is reported to the public in the United States?

A) millibars
B) Newtons
C) kilopascals
D) inches of mercury

Question 16

The wind speed normally increases with height in the layer of air next to the ground. This illustrates the fact that:

A) density decreases with height.
B) friction is present only close to the ground.
C) pressure decreases with height.
D) the lowest part of the atmosphere is turbulent.
E) temperature decreases with height.

Question 17

Which of the following has the smallest impact on winds?

A) friction
B) Coriolis effect
C) pressure gradient force
D) humidity

Question 18

The term pressure gradient refers to:

A) change in pressure from the tropopause to sea level.
B) change in pressure at a weather station over 3 hours time.
C) change in pressure along a horizontal surface.
D) change in wind speed at the same station.
E) highest and lowest pressures at a station.

Question 19

What do isobars represent on a map?

A) the lowest pressures on the map
B) lines connecting points of equal air pressure
C) the highest pressures on the map
D) areas of convergence in the upper atmosphere

Question 20

-Refer to the map above. What best explains the high wind speeds found immediately around the low pressure center (L)?

A) the higher humidity associated with low pressures
B) the dramatically lower temperatures in the area
C) increased friction
D) the comparatively high pressure gradient in the area

Question 21

You would expect vertical airflow in a cyclone to result in:

A) convergence aloft.
B) divergence aloft.
C) no cloud development.
D) divergence at the surface.

Question 22

An altimeter is an adaptation of the:

A) anemometer.
B) aneroid barometer.
C) millibar.
D) mercurial barometer.

Question 23

What is the average sea level pressure in the United States?

A) 1000.13 mb
B) 766.00 mb
C) 1013.25 mb
D) 29.92 mb

Question 24

A plane takes off from City A headed for City B, located directly to the north. The pilot flies directly north following a straight line, but arrives at a city some distance to the west of City B. What can be said of the airplane?

A) It was flying in the Southern Hemisphere.
B) It probably has a broken compass.
C) It was blown off course by upper atmospheric winds.
D) It was flying in the Northern Hemisphere.

Question 25

The overall strength of a circulation system is determined by:

A) the latitude.
B) its pressure gradient.
C) no one factor is more important than the others.
D) air temperature.
E) friction between the ground and the air.

Question 26

The effect of friction on the wind directly and/or indirectly alters its:

A) heat content.
B) speed and direction.
C) density.
D) viscosity.
E) speed only.

Question 27

Meteorologists convert all atmospheric pressure data to the equivalent sea- level air pressure in order to:

A) correct for the effects of the Coriolis force.
B) unify the pressure gradient force at all locations.
C) make sure all of the data is measured in millibars.
D) remove the effects of elevation.

Question 28

The pressure gradient force is directed from higher to lower pressure:

A) only at the equator.
B) everywhere except the equator.
C) only at the poles.
D) only in the Northern Hemisphere.
E) everywhere.

Question 29

As seen by an observer on Earth, the Coriolis effect is an illusion; no deflection can actually be measured.

A) false, but only near the poles
B) true
C) true, but only near the poles
D) false

Question 30

If the National Weather Service converted to the metric system, they would most likely report air pressure in which units?

A) pascals
B) millibars
C) inches of mercury
D) kilopascals

Question 31

Which of the following would involve the greatest change in atmospheric pressure?

A) difference between the highest and lowest recorded pressure at any one weather station
B) travel from center of a low pressure system to center of a high pressure system
C) horizontal airplane flight of 200 miles
D) balloon ascent from sea level to 3 miles

Question 32

What does Buys Ballot's Law state?

A) If you stand with your back to the wind, there is low pressure on your right and high pressure on your right.
B) If you stand with your back to the wind, there is low pressure directly in front of you.
C) If you stand facing into the wind and you are facing north, the wind is geostrophic.
D) If you stand with your back to the wind, there is low pressure on your left and high pressure on the right.

Question 33

The force that generates wind is:

A) centrifugal force.
B) friction.
C) pressure gradient force.
D) gravity.
E) Coriolis force.

Question 34

If you want to locate the centers of high and low pressure systems, you will need a map that has:

A) isodrosotherms.
B) contour lines.
C) isotherms.
D) isobars.

Question 35

Identify the choice above that represents high pressure center in the Southern Hemisphere.

A) graph a
B) graph b
C) graph c
D) both a and b
E) none of these

Question 36

Which type of meteorological instrument is used to collect the necessary data for the production of upper- level weather charts?

A) radiosonde
B) mercury barometer
C) altimeter
D) hygrometer

Question 37

The maximum pressure range of the atmosphere, as defined by the highest and lowest pressures ever recorded, is between:

A) 0- 1000 millibars.
B) 720- 1335 millibars.
C) 660- 1335 millibars.
D) 870- 1085 millibars.
E) 975- 1035 millibars.

Question 38

Air pressure drops __________ with altitude in a column of cold (dense) air than in a column of warm (less dense) air.

A) equally
B) more slowly
C) more rapidly
D) less significantly

Question 39

The National Weather Service measures air pressure in the unit of a millibar, which is equivalent to:

A) 500 Newtons per square meter.
B) 10 Newtons per square meter.
C) 1000 Newtons per square meter.
D) 100 Newtons per square meter.

Question 40

Who invented the mercury barometer?

A) Celsius
B) Bergeron
C) Galileo
D) Toricelli

Question 41

Cyclonic airflow is characterized by:

A) convergence aloft and divergence at the surface.
B) divergence both at the surface and aloft.
C) convergence both at the surface and aloft.
D) divergence aloft and convergence at the surface.

Question 42

An aerovane is commonly used to measure:

A) wind direction only.
B) wind speed only.
C) both wind direction and wind speed.
D) pressure gradient force only.

Question 43

What is a limitation of an altimeter that pilots must account for?

A) It has a low battery life at high altitudes.
B) Its readings may be too low or too high if the temperature varies from the expected.
C) They can't ever be used to determine altitude - only pressure.
D) Corrections are not as accurate at low levels as they are at higher levels.

Question 44

The Coriolis effect occurs because of this characteristic of the earth:

A) its atmosphere.
B) its rotation.
C) its dense core.
D) its magnetic field.

Question 45

-Refer to the map above. The labeled lines on the map are called and they represent lines of equal .

A) isobars; pressure
B) isotherms; temperature
C) isodrosotherms; humidity
D) isotherms; pressure

Question 46

The Coriolis effect influences the wind by:

A) increasing the wind speed.
B) changing the direction of the wind.
C) decreasing the wind speed.
D) starting the air motion.

Question 47

Which of these factors influence the magnitude of the Coriolis force?

A) latitude
B) wind speed
C) wind direction
D) both wind speed and latitude

Question 48

-Identify the choice above that represents low pressure center in the Northern Hemisphere.

A) graph a
B) graph b
C) graph c
D) both a and b
E) none of these

Question 49

Weather reports of wind express only the horizontal motion of the air. The vertical component of the air motion is usually:

A) very much slower.
B) about the same.
C) only slightly slower.
D) much faster.
E) No general statement can be made.

Question 50

_______are elongated high pressure areas extending towards the poles and are associated with_______ .

A) troughs; warm, dry air
B) ridges; cool, wet weather
C) troughs; cool, wet weather
D) ridges; warm, dry air

Question 51

You would expect vertical airflow in an anticyclone to result in:

A) convergence aloft.
B) convergence at the surface.
C) clouds.
D) divergence aloft.

Question 52

When representing wind direction numerically, winds from the north are associated with:

A) 0 degrees.
B) 235 degrees.
C) 90 degrees.
D) 180 degrees.

Question 53

The geostrophic wind concept is most like the real atmospheric winds:

A) at high altitudes.
B) near the surface.
C) in an anticyclone.
D) in a cyclone.
E) near the equator.

Question 54

The best explanation for the cause of atmospheric pressure is:

A) air compression.
B) air density.
C) air temperature.
D) wind force.
E) weight of the air above.

Question 55

Why is the 500- mb level chart important for forecasting?

A) It helps determine surface temperatures.
B) It helps determine the appropriate rate of adiabatic cooling.
C) It demonstrates cloud cover.
D) The winds at the 500- mb level determine the direction of movement for weather systems.

Question 56

-Refer to the map above. Which of the following areas is most likely to be experiencing rain or other significant weather?

A) the Southwest
B) Western Canada
C) the Pacific Northeast
D) the Great Lakes region

Question 57

A cyclone is generally defined by meteorologists as:

A) a tornado on the ground.
B) an intense, violent storm.
C) an area of high pressure.
D) an area of low pressure.

Question 58

The Coriolis effect is important only for motions that:

A) cover short distances.
B) do not involve a pressure gradient.
C) are near the earth's surface.
D) are slow.
E) cover long distances.

Question 59

High air pressure zones are usually associated with:

A) relatively dry conditions.
B) stormy weather.
C) ascending currents.
D) converging winds.

Question 60

According to researchers at University of Colorado Denver, what was the most important factor in the high number of home runs at Coors Field?

A) The predominant summer wind direction is in favor of the batter.
B) The thin air allows the batter to obtain better auditory cues about the pitch.
C) The thin air allows the ball to fly further.
D) The lower temperatures help athletes not to overheat.

Question 61

When upper atmospheric winds blow parallel to the isobars along straight paths, they are termed___________ winds.

Question 62

What is a wind rose?

Question 63

In the northern hemisphere, cyclonic winds flow:

A) outward and counterclockwise.
B) inward and counterclockwise.
C) inward and clockwise.
D) outward and clockwise.

Question 64

The spacing of isobar lines on a map provides a visual indication of_______ .

Question 65

Horizontal variations in air pressure cause a force which makes the wind blow. These pressure variations are often caused by:

A) warm temperatures in the stratosphere.
B) Earth's rotation.
C) non- circular shape of Earth.
D) greenhouse effect.
E) uneven heating of the earth's surface.

Question 66

How does friction act to change the direction of the wind near the earth's surface?

Question 67

If air pressure is reduced by one- half for every five- kilometer increase in altitude, what would be the air pressure at a height of 25 kilometers as a fraction of sea- level air pressure?

A) 1/64
B) 1/8
C) 1/16
D) 1/32

Question 68

The horizontal movement of air is called______ .

Question 69

Why are clouds and precipitation associated with surface low pressure systems?

Question 70

Neglecting friction, the speed and direction of the horizontal wind are determined by:

A) pressure gradient and Coriolis.
B) only gravity.
C) viscosity and turbulence.
D) gravity and humidity.
E) temperature and humidity.

Question 71

Instead of the air flowing straight out of a high pressure system, it spirals out in a clockwise direction. The cause of the clockwise spiraling motion is:

A) inertia.
B) turbulence.
C) pressure gradient force.
D) Coriolis force.
E) centripetal force.

Question 72

The primary force which causes ALL winds is:

A) Coriolis effect.
B) pressure gradient force.
C) geostrophic force.
D) centrifugal force.
E) inertia force.

Question 73

The addition of water vapor will cause the density of air to:

A) increase.
B) vary widely in a horizontal direction.
C) stay the same.
D) decrease.

Question 74

-Which option above is generally associated with "fair" weather?

A) graph a
B) graph b
C) graph c
D) both a and b
E) none of these

Question 75

-Identify the choice above that represents a low pressure center (in either hemisphere).

A) graph a
B) graph b
C) graph c
D) both a and b
E) none of these

Question 76

Name the three driving forces that create and influence the air's motion, and write a brief description of how each creates and/or alters wind.

Question 77

If "fair" weather is approaching, the pressure tendency would probably be:

A) steady.
B) rising.
C) falling.
D) Pressure tendency has nothing to do with forecasting good or bad weather.

Question 78

In the southern hemisphere, anticyclonic winds flow:

A) inward and clockwise.
B) outward and clockwise.
C) outward and counterclockwise.
D) inward and counterclockwise.

Question 79

What is the fundamental cause of horizontal pressure differences in the atmosphere?

Question 80

A wind rose is used to identify:

A) prevailing wind direction.
B) locations with similar wind directions during a storm.
C) wind direction at a given moment.
D) the approximate degree of Coriolis deflection at a specific location.