Deck 18: Air Pressure and Wind

Question 1

Closely spaced isobars indicate ________.

A)high pressure gradient and high winds
B)high pressure gradient and likely gusty winds
C)geostrophic conditions
D)low pressure gradient and weak gusty winds

Answer 1

A

Question 2

Widely spaced isobars often indicate ________.

A)high winds
B)variable winds
C)light winds
D)cyclonic winds

Answer 2

C

Question 3

A steep pressure gradient ________.

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

Answer 3

B

Question 4

If "fair" weather were approaching,the pressure tendency would probably be ________.

A)steady
B)rising
C)falling
D)none of these

Question 5

The Coriolis effect influences ________.

A)only wind speed
B)only wind direction
C)both wind speed and wind direction
D)neither wind speed nor wind direction

Question 6

In the Southern Hemisphere,the winds associated with a low pressure system blow ________.

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

Question 7

You are watching the local weatherman on TV.You live in mid-latitudes in North America,and the weatherman says the winds aloft are blowing toward the northwest.Is this reasonable?

A)Yes,southeast winds are common at mid latitudes in North America.
B)Yes,northwest winds are common at mid latitudes in North America.
C)No,Northern Hemisphere winds aloft always move from west to east because of the Coriolis force.
D)No,mid-latitude winds always move from east to west because of the Coriolis force.

Question 8

Standard sea level pressure in inches of mercury is ________.

A)7)52 inches
B)14.70 inches
C)28.70 inches
D)29.92 inches

Question 9

Isobars are lines on a weather map representing what?

A)lines of equal air pressure
B)lines of equivalent air speed
C)lines of equal elevation for the tropopause
D)lines showing equal density of bars

Question 10

A weather system is moving from west to east.You look at a weather map and see that you are in an area of closely spaced isobars with the center just to your east,but the spacing of the isobars increases away from you.What would you forecast for wind conditions?

A)Winds will stay the same.
B)Winds will increase.
C)Winds will decrease.
D)Winds will increase then decrease.

Question 11

Which of these instruments is not used to measure air pressure?

A)mercurial barometer
B)aneroid barometer
C)barograph
D)anemometer

Question 12

Upper air winds ________.

A)are generally faster than surface winds
B)are unaffected by the Coriolis force
C)are greatly influenced by friction
D)both A and B

Question 13

An altimeter is an adaptation of the ________.

A)mercurial barometer
B)aneroid barometer
C)barograph
D)anemometer

Question 14

When Hurricane Katrina was a category 5 hurricane at its peak strength,the air pressure in the eye of the storm was 902mb.Near the earth's surface,the air pressure falls off at roughly 100mb per kilometer.So if you had an uncorrected altimeter in the eye of Katrina at sea level (not a good place to be),what altitude would it have read?

A)10,000 m
B)2010 m
C)1020 m
D)115 m

Question 15

Low air pressure systems are usually associated with ________.

A)diverging surface winds and low pressure aloft
B)descending air and low pressure aloft
C)converging air,precipitation,and high pressure aloft
D)clear weather

Question 16

The mercurial barometer was invented by ________.

A)Torricelli
B)Galileo
C)Newton
D)Watt

Question 17

Inches of mercury is something that would only be used in America.Elsewhere in the world,the mercury height would be in millimeters,or about 760mm (76cm).Mercury has a density of about 13.56 g/cm3,or in other words,each cm of mercury weighs about 13,300 dynes.So 760mm of mercury weighs 1,013,000 dynes.1 mb is 1 dyne/cm2,so what is the air pressure in mb?

A)760 mb
B)1,000,000 mb
C)1013 mb
D)1)013 mb

Question 18

The force that generates wind is ________.

A)Coriolis force
B)gravity force
C)centrifugal force
D)pressure gradient force

Question 19

You might wonder why a millibar isn't exactly 1/1000th of an atmosphere.The unit is actually related to the old CGS units because atmospheric pressure is close to this unit.In CGS units 1 bar = 1000 dynes/cm2.Pressure is often incorrectly reported as kg/cm2,which is neither a legitimate pressure unit nor a standard SI unit (pressure is force/unit area,and kg are a mass unit,and SI units never mix kg and cm).So let's straighten out your friends on these units.Standard air pressure in this incorrect unit is 1.034 kg/cm2.The weight of a kg at the earth's surface is 980,000 dynes.So what is standard air pressure in millibars?

A)750 mb
B)890 mb
C)1013 mb
D)1143 mb

Question 20

Where is the Coriolis force greatest?

A)low latitude
B)high latitude
C)anywhere air moves north or south
D)intermediate latitudes

Question 21

The Sahara and Australian deserts (among others)are associated with the ________.

A)subtropical high
B)equatorial low
C)subpolar low
D)polar high

Question 22

You are on a boat in a fiord in Glacier Bay,Alaska.It is a clear sunny day with temperatures near 20°C with no wind.Within 5 minutes the sky is still clear but the wind is blowing at 30 knots down valley,the sea is filled with whitecaps,and the temperature drops to 5°C.What just happened?

A)You experienced a Chinook wind.
B)You experienced a valley wind,caused by cold air spilling off an ice cap down the valley.
C)You experienced an afternoon sea breeze,blowing cold air off the ocean.
D)A storm front must have passed.

Question 23

In the Northern Hemisphere,winds associated with a high pressure system blow ________.

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

Question 24

Tropical cyclones (aka hurricanes in the Atlantic)are intense low-pressure systems characterized by heavy rain and high winds.When a tropical cyclone passes an area,however,there are generally several days of clear,dry weather.Why might this occur?

A)The hurricane carries a cold front with it,which carries dry air.
B)The cyclone has sucked up all the moist air around it,leaving dry air behind.
C)The cyclone must have an outflow aloft,which feeds descending air surrounding the storm.
D)The spiral arms of the hurricane are storm fronts,and each carries descending air behind it.

Question 25

Another name for the area of equatorial low pressure is the ________.

A)subpolar easterlies
B)westerlies
C)doldrums
D)horse latitudes

Question 26

Most of the United States is situated in which zone of prevailing winds?

A)trade winds
B)subpolar easterlies
C)westerlies
D)doldrums

Question 27

A Santa Ana (or Chinook or Foehn)wind is a ________.

A)wind associated with a blizzard
B)cold,damp wind blowing off a snow field
C)wind that is common to the world's deserts
D)very dry,warm wind flowing down a mountain slope

Question 28

When are upper air winds fastest?

A)in summer
B)in winter
C)whenever the temperature gradient is weak
D)These winds maintain roughly the same speeds throughout the year.

Question 29

Tropical cyclones produce the most intense low-pressure systems on earth.To develop and maintain this low pressure,what must happen aloft in this type of storm?

A)A strong jet stream flow must be present to maintain the inward flow.
B)A strong divergent flow (outflow)aloft must keep up with,or exceed,the inflow near the surface.
C)The storm must push the tropopause far into the stratosphere to maintain the low pressure.
D)Rain must fall to force thunderstorms to collapse to keep the air circulation going.

Question 30

A sea breeze usually originates during the ________.

A)evening and flows toward the land
B)day and flows toward the land
C)evening and flows toward the water
D)day and flows toward the water

Question 31

Asia has an intense monsoon,but North America also experiences a low-intensity monsoon.What causes monsoons?

A)Heating of the polar regions in summer due to long days causes air to flow toward the poles in summer,drawing moisture from warm ocean dominated air masses.
B)The heating of the continent during the summer produces a persistent low pressure over the continent that draws warm moist air masses from adjacent oceans.
C)The oceans warm faster than the continents during the summer and spawn cyclonic storms that move toward the continents.
D)The horse latitude high pressure system breaks down in summer,leading to monsoon moisture in desert locations like southwestern North America and India.

Question 32

A land breeze usually originates during the ________.

A)evening and flows toward the land
B)day and flows toward the land
C)evening and flows toward the water
D)day and flows toward the water

Question 33

In the Northern Hemisphere,the winds associated with a low pressure system (cyclone)blow ________.

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

Question 34

This pressure zone is associated with abundant precipitation and warm temperatures.

A)subtropical high
B)equatorial low
C)subpolar low
D)polar high

Question 35

Why do storm systems move from west to east in mid latitudes of the Northern Hemisphere?

A)The storms are steered by approximately west to east winds aloft that are approximately geostrophic winds produced by Coriolis forces.
B)The prevailing wind is from the west.
C)The prevailing wind is from the east,and the storm systems move toward the surface flow.
D)The continents break up air flow that would normally be south to north and the Coriolis force turns the storms to the right,or toward the east.

Question 36

If stormy weather were approaching,the pressure tendency would probably be ________.

A)steady
B)rising
C)falling
D)none of these

Question 37

The subpolar low (polar front)is ________.

A)a zone where the trade winds meet
B)the forward edge of the Antarctic ice cap
C)a zone where the polar easterlies and the westerlies converge
D)the boundary between frozen and liquid

Question 38

Fast moving currents of air found near the top of the troposphere are called ________.

A)jet streams
B)chinooks
C)mesocyclones
D)El Niño

Question 39

High air pressure systems are usually associated with ________.

A)diverging winds
B)descending air
C)clear weather
D)all of these

Question 40

Which of the following is not true for anticyclonic storms systems in the Northern Hemisphere?

A)The outward flow produces a clockwise circulation due to the Coriolis force.
B)The storm system is characterized by high pressure and descending air.
C)The storm system is characteristic of mid-latitude zones and is typically associated with fair weather.
D)The storm system is a low-latitude phenomena associated with outflow from tropical cyclones.

Question 41

Why is the Santa Ana wind a danger signal in southern California?

A)It is a cold,dry winter wind that brings danger of hypothermia to people like the homeless living on the streets.
B)It drives people crazy with the howling winds,so crime goes up.
C)It is a warm,humid wind from Mexico that signals El Niño conditions and high potential for flooding.
D)It is a warm,dry wind that can quickly dry out brushlands and spread fires.

Question 42

The Coriolis effect influences wind speed but not wind direction.

Question 43

The pressure gradient force is the driving force behind wind.

Question 44

equatorial low trade winds polar front subtropical high

Question 45

Standard sea level air pressure is 29.92 inches of mercury.

Question 46

Standard sea level air pressure is 1013 millibars.

Question 47

Which of the following devices measures both wind direction and speed?

A)anemometer
B)wind vane
C)wind sock
D)None of these can measure both wind speed and direction.

Question 48

Coriolis effect jet stream friction pressure gradient force

Question 49

If the barometer indicated 1020 millibars,air pressure would be considered high.

Question 50

sea breeze Chinook winds valley breeze trade winds

Question 51

Where was the El Niño phenomena first recognized?

A)the Caribbean region
B)California
C)Central America
D)Peru and Ecuador

Question 52

trade winds westerlies Chinook polar easterlies

Question 53

Torricelli invented the mercurial barometer.

Question 54

If you live on the east coast of Florida or the Gulf Coast,why might you hope for an El Niño year?

A)It will decrease the chances of heavy summer thunderstorms and floods.
B)It will decrease the probability of tropical cyclones.
C)It will bring clear,cool summer conditions,albeit dry.
D)It will produce a warmer summer,but with less rain than normal.

Question 55

What is the Southern Oscillation?

A)the intermittent switch from El Niño to La Niña conditions in the equatorial Pacific
B)the periodic intense cyclonic storms from Antarctica
C)the weather pattern that changes tropical cyclone activity in the southern ocean
D)the 10-year cycle in winter storm activity in the temperate zone of the Southern Hemisphere

Question 56

The most precise instrument for measuring wind speed is a ________.

A)cup anemometer
B)wind vane
C)wind sock
D)wet bulb/dry bulb thermometer

Question 57

When someone says we have a southeast wind,what direction would you look to face into the wind?

A)southeast
B)northwest
C)east
D)west

Question 58

The Coriolis effect is strongest at the equator and diminishes in strength poleward.

Question 59

If you live in southwestern North America and are experiencing drought conditions,what do you hope will happen?

A)A La Niña period will begin.
B)An El Niño period will begin.
C)Conditions will return to a normal,with neither La Niña nor El Niño.
D)The temperatures will decrease in the eastern equatorial Pacific.

Question 60

The Amargosa Valley in eastern California desert often experiences a cold evening wind that blows downvalley.Which of the following might explain this phenomenon?

A)Daytime heating causes a local low pressure that causes air to rush in by evening.
B)Moist Pacific air rising over the Sierra Nevada Mountains produces mountain precipitation,and as this air spills off the eastern escarpment,it forms the valley wind.
C)Night time cooling upvalley produces a cold,unstable air mass that is funneled down the valley to produce a valley wind.
D)It is a nighttime land breeze and there should be an accompanying daytime seabreeze up valley.

Question 61

A southwest wind blows toward the northeast.

Question 62

The ultimate cause of a sea breeze is the unequal heating of land and water.

Question 63

The existence of jet streams was first determined by Ben Franklin as a result of his kite experiments.

Question 64

If the earth rotated twice as fast as it does,the Coriolis force would be half as much as on Earth.

Question 65

Cyclones are usually associated with stormy weather.

Question 66

Most deserts are associated with the subtropical high.

Question 67

If the earth were not rotating,there would be no Coriolis force.

Question 68

Upper air winds are generally faster than the surface winds directly below.

Question 69

Anticyclones characteristically have winds blowing out from their centers.

Question 70

In the Northern Hemisphere,winds blow clockwise and outward from the center of anticyclones.

Question 71

An isobar is a line connecting places of equal humidity.

Question 72

The region where the trade winds meet is also called the doldrums.

Question 73

High pressure systems are usually associated with stormy weather.

Question 74

A surface low pressure system will not strengthen unless there is high pressure aloft.

Question 75

Most of the people living in the United States are under the influence of the wind belt known as the westerlies.

Question 76

Low pressure at the surface also requires low pressure aloft for air to continue to flow toward the low.

Question 77

Low pressure systems are usually associated with clear weather.

Question 78

Horizontal movement of air is called wind.

Question 79

Of the various elements of weather,changes in air pressure are probably the most obvious.

Question 80

Closely spaced isobars indicate high wind speeds.