Deck 8: Air Pressure and Winds

Question 1

If the earth's gravitational force were to increase,atmospheric pressure at the ground would

A) increase.
B) decrease.
C) remain the same.
D) cause the atmosphere to expand vertically.

Answer 1

A

Question 2

Which of the following instruments measures pressure?

A) barometer
B) thermometer
C) radiometer
D) hygrometer
E) densitometer

Answer 2

A

Question 3

Warm air aloft is associated with constant pressure surfaces that are found at ____ altitude than normal and ____ than normal atmospheric pressure aloft.

A) higher,higher
B) higher,lower
C) lower,higher
D) lower,lower

Answer 3

A

Question 4

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 ____ than in the cold column.

A) decrease,more rapidly
B) decrease,more slowly
C) increase,more rapidly
D) increase,more slowly

Question 5

The contour lines drawn on a 500 mb chart are lines of constant

A) pressure.
B) altitude.
C) density.
D) wind direction.

Question 6

The surface pressures at the bases of warm and cold columns of air are equal.Which of the following statements is not correct?

A) Pressure will decrease with increasing height at the same rate in both columns.
B) The cold air is denser than the warm air.
C) Both columns of air contain the same total number of air molecules.
D) The weight of each column of air is the same.

Question 7

The unit of pressure most commonly found on a surface weather map is

A) inches of mercury.
B) millibars or hectopascals.
C) pounds per square inch.
D) atmospheres.

Question 8

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?

A) 840 mb
B) 930 mb
C) 1,020 mb
D) 1,830 mb

Question 9

Net convergence of air would cause surface pressure to ____ and net divergence would cause surface pressure to ____.

A) increase,decrease
B) increase,increase
C) decrease,decrease
D) decrease,increase

Question 10

Which of the following relationships best describes the gas law?

A) Pressure is proportional to density times temperature.
B) Density is proportional to pressure times temperature.
C) Temperature is proportional to density times pressure.
D) Temperature times pressure times density remains constant.

Question 11

Suppose a very cold parcel of air at 5.5 km (18,000 feet)is compared to a similar (but warm)parcel of air at sea level.Which of the following would be true?

A) The parcel at sea level has higher pressure and higher density.
B) The parcel at sea level has lower pressure and higher density.
C) The parcel at sea level has lower pressure and lower density.
D) The parcel at sea level has higher pressure and lower density.

Question 12

Pressure changes

A) more rapidly in the horizontal direction than in the vertical.
B) more rapidly in the vertical direction than in the horizontal.
C) at the same rate in the horizontal and vertical directions.
D) more rapidly in the vertical over land than over the ocean.

Question 13

Lines connecting points of equal pressure are called

A) isobars.
B) millibars.
C) contours.
D) isotherms.
E) a coordinate grid.

Question 14

To correctly monitor horizontal changes in air pressure,the most important correction for a mercury barometer is the correction for

A) temperature.
B) altitude.
C) density.
D) gravity.

Question 15

Low ____ on a constant height chart corresponds to low ____ on a constant pressure chart.

A) pressures,pressures
B) pressures,heights
C) heights,pressures
D) heights,heights

Question 16

On an isobaric surface,

A) altitude is constant.
B) temperature is constant.
C) pressure is constant.
D) a and c

Question 17

If two air parcels at sea level have the same size but different temperatures,the colder parcel of air will have

A) a higher pressure but the same density as the warm parcel.
B) the same pressure but lower density than the warm parcel.
C) the same pressure but higher density than the warm parcel.
D) a lower pressure but the same density as the warm parcel.

Question 18

The scale on an altimeter indicates altitude,but an altimeter actually measures

A) temperature.
B) density.
C) pressure.
D) humidity.

Question 19

On a 500 millibar chart,____ are drawn to represent horizontal changes in altitude which correspond to horizontal changes in pressure.

A) contour lines
B) isobars
C) isotherms
D) isotachs

Question 20

Suppose a parcel of air has a given temperature,pressure,and density.If the parcel's size remains the same while its temperature increases,then the air pressure inside the parcel will

A) decrease.
B) decrease to but not lower than 1,000 mb.
C) increase.
D) remain constant.

Question 21

Which of the following forces cannot act to change the speed of the wind?

A) pressure gradient force
B) frictional force
C) Coriolis force
D) none of the above

Question 22

If the earth stopped rotating,which of the following would not be true?

A) Surface winds would below from high toward low pressure.
B) There would still be a Coriolis force.
C) There would still be a pressure gradient force.
D) There would still be a gravitational force.

Question 23

The force that would cause a stationary parcel of air to begin to move horizontally is called the

A) Coriolis force.
B) pressure gradient force.
C) centripetal force.
D) frictional force.

Question 24

The Coriolis force is the force that causes the wind to blow.

Question 25

On an isobaric weather chart,the spacing of the height contours indicates the magnitude of the pressure gradient force.

Question 26

Which of the statements below is not correct concerning the pressure gradient force?

A) The PGF points from high to low pressure in the Northern Hemisphere.
B) It is non-existent at the equator.
C) It can cause the wind to speed up or slow down.
D) The PGF points from high to low pressure in the Southern Hemisphere.

Question 27

Which of the following forces does not have a direct effect on horizontal wind motions?

A) pressure gradient force
B) frictional force
C) gravitational force
D) Coriolis force

Question 28

Which statement below is not correct concerning the Coriolis force?

A) It causes the winds to deflect to the right in the Northern Hemisphere.
B) It is strongest at the equator.
C) It can cause winds to change direction,but not to increase or decrease in speed.
D) It deflects winds in opposite directions in the Northern and Southern Hemispheres.

Question 29

A surface low pressure center is generally associated with ____ on an upper level isobaric chart.

A) a trough
B) a ridge
C) zonal flow
D) convergence

Question 30

On an upper-level chart,normally we find warm air associated with ____ pressure,and cold air associated with ____ pressure.

A) high,high
B) high,low
C) low,low
D) low,high

Question 31

During a reversible adiabatic process,the pressure gradient force is parallel to the isobars.

Question 32

On an upper-level chart the wind tends to blow

A) at right angles to the isobars or contour lines.
B) parallel to the isobars or contours.
C) at an angle between 10 and 30 to the contours and towards lower pressure.
D) at constant speed.

Question 33

Suppose that the winds aloft are geostrophic and blowing from the north.Low pressure is located to the

A) north.
B) south.
C) east.
D) west.

Question 34

The ____ is an apparent force created by the earth's rotation.

A) pressure gradient force
B) Coriolis force
C) centripetal force
D) gravitational force

Question 35

The amount of pressure change that occurs over a given horizontal distance is called the

A) pressure tendency.
B) Coriolis parameter.
C) pressure gradient.
D) potential gradient.
E) slope.

Question 36

Which of the following can influence wind direction?

A) Coriolis force
B) pressure gradient force
C) centripetal force
D) all of the above

Question 37

Which of the following produces the strongest Coriolis force?

A) fast winds,low latitude
B) fast winds,high latitude
C) slow winds,low latitude
D) slow winds,high latitude

Question 38

A ridge on an upper-level isobaric chart indicates

A) higher-than-average heights.
B) lower-than-average heights.
C) average heights.
D) a region with calm winds.

Question 39

The pressure gradient force is directed from higher pressure toward lower pressure

A) only at the equator.
B) at all places on earth except for the equator.
C) only in the Northern Hemisphere.
D) only in the Southern Hemisphere.
E) at all places on earth.

Question 40

The Coriolis force is the result of

A) wind.
B) rotating earth.
C) day/night temperature contrasts.
D) gravitational force exerted by the moon as it orbits the earth.
E) the poles being colder than the equator.

Question 41

If,at your home in the Northern Hemisphere,the surface wind is blowing from the northwest,then the region of lowest pressure will be to the ____ of your home.

A) north
B) south
C) east
D) west

Question 42

Suppose you deflate a bicycle tire by depressing the air valve.Why does air rush out of the tire? After the air stops rushing out of the tire,is the tire empty? Explain your answer.

Question 43

The vertical pressure gradient force is directed

A) downward.
B) upward.
C) horizontally.

Question 44

Surface winds blow across the isobars at an angle due to

A) the Coriolis force.
B) the pressure gradient force.
C) the frictional force.
D) the centripetal force.

Question 45

Under what conditions might a station pressure of 750 mb be observed?

Question 46

If the earth were to begin rotating in the other direction,would air still rise in the center of surface low pressure?

Question 47

Briefly explain the principle of the mercury barometer.Mercury is relatively expensive and toxic.Why do you think mercury is used in barometers instead of another fluid such as water?

Question 48

The wind around a surface low pressure center in the Southern Hemisphere blows

A) counterclockwise and outward from the center.
B) counterclockwise and inward toward the center.
C) clockwise and outward from the center.
D) clockwise and inward toward the center.

Question 49

Sketch the wind flow patterns around surface high and low pressure centers in the Northern and Southern Hemispheres.

Question 50

If directly above you at 10,000 feet the wind is blowing from the south,then it is a good bet that at 10,000 feet,the center of lowest pressure is ____ of you,while the center of highest pressure is ____ of you.

A) west,east
B) south,north
C) east,west
D) north,south

Question 51

The winds aloft in the middle latitudes of the Southern Hemisphere generally blow

A) from west to east.
B) from east to west.
C) from north to south.
D) from south to north.

Question 52

Winds blow slightly inward

A) around surface low pressure centers in the Northern Hemisphere only.
B) around surface low pressure centers in the Southern Hemisphere only.
C) around surface low pressure centers in the Northern and Southern Hemispheres.
D) at the poles in both hemispheres.

Question 53

We can generally expect the air to be ____ above areas of surface low pressure and ____ above areas of surface high pressure.

A) rising,rising
B) rising,sinking
C) sinking,sinking
D) sinking,rising

Question 54

The wind around a surface high pressure center in the Northern Hemisphere blows

A) counterclockwise and outward from the center.
B) counterclockwise and inward toward the center.
C) clockwise and outward from the center.
D) clockwise and inward toward the center.

Question 55

Suppose you stand outside and feel a fresh breeze blowing against your face.Could this be a geostrophic wind? Explain.

Question 56

What differences might you expect to see between the weather conditions depicted on the surface in your city and at the 500 mb level above your city?

Question 57

A surface low pressure area that moves from south to north directly east of your home would most likely produce winds that shift from

A) S to SE to E.
B) SE to E to SW.
C) N to NE to E.
D) W to NW to N.
E) NE to N to NW.

Question 58

The pressure announced on last night's television weather broadcast was 29.92.Explain how this was measured and give the units.Would this be considered an unusually large or low pressure value?

Question 59

Is a force needed to keep a satellite orbiting at constant speed around the earth?

Question 60

Explain briefly why upper-level winds at middle latitudes in the Northern Hemisphere blow from west to east.In what direction do upper level winds at middle latitudes in the Southern Hemisphere blow?

Question 61

Explain why closely-spaced contour lines on an upper-level isobaric chart are associated with fast winds.

Question 62

Explain why it is often windy at the beach.What forces are responsible,and how do beachfront conditions differ from conditions farther inland?

Question 63

If the earth did not rotate,how would you expect winds to blow with respect to high and low pressure centers?

Question 64

Draw a simple Northern Hemisphere upper-air pressure pattern consisting of several straight,uniformly-spaced contour lines running from left to right across your paper.Assume that lower heights are found at the top of your chart.Use arrows to indicate the direction that the wind would blow and the direction of the pressure gradient force and Coriolis force acting on a moving parcel of air.

Question 65

Explain why strong upper-level divergence will cause the pressure in the center of a surface low to decrease.