Meteorology Practice/test Exam 2

Front 1

The fog that commonly forms along the West Coast of North America is ________.

Back 1

advection fog

Front 2

In middle and high latitudes, the most effective method of precipitation formation is ________.

Back 2

the ice crystal process

Front 3

Large raindrops fall ________ than smaller raindrops and have a ________ terminal velocity than small raindrops.

Back 3

faster; greater

Front 4

What type of precipitation would most likely form when a deep layer of air is above freezing and a shallow layer of air just above the ground is slightly below freezing?

Back 4

Freezing rain.

Front 5

What is sleet?

Back 5

Precipitation that has frozen before it reached the ground.

Front 6

Weather radar is used to identify the ________, ________, and ________ of precipitation.

Back 6

intensity; location; amount

Front 7

The intensity of snowfall is based on ________.

Back 7

Visibility

Front 8

A station at an altitude of 900m above sea level measures an air pressure of 930mb. Under normal conditions, which of the values below do you think would be the most realistic [sea level pressure] for this station?

• 800mb
• 930mb
• 1000mb
• 2000mb

Back 8

1000mb

Front 9

Two places at the same elevation have the same sea level pressure but at station A, the surface temperature is 5°C while at station B, the surface temperature is 20°C. If all other things remain constant, at 1000 meters above the surface, the pressure as station A would be [less/greater than or same] as the pressure station B.

Back 9

less than

Front 10

Low ________ on a constant elevation map corresponds to low ________ on a constant pressure map.

Back 10

pressure; height

Front 11

Which of the follow produces the weakest Coriolis force?

• fast winds, low latitude
• fast winds, high latitude
• slow winds, low latitude
• slow winds, high latitude

Back 11

slow winds, low latitude

Front 12

At your home in the Northern Hemisphere, the winds at 500mb are geostrophic and blowing from the south. With the same orientation of isobars at the [surface], the winds at your home would blow from the ________.

Back 12

southeast

Front 13

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

Back 13

pressure gradient

Front 14

In the Southern Hemisphere, at the surface, the wind around a high pressure area blows ________ and ________

Back 14

counterclockwise and outward

Front 15

A wind that blows at a constant speed parallel to straight isobars is a ________ wind.

Back 15

geostrophic

Front 16

On an upper level map, winds tend to blow...

Back 16

parallel to the contour lines (whether curved or straight)

Front 17

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

Back 17

rising; sinking

Front 18

In summer, where would you expect to find semipermanent low pressure areas?

Back 18

Over land, because in summer the land tends to be warmer than the ocean.

Front 19

In the three-cell model of the general circulation, areas of surface high pressure should be found at...

Back 19

30° latitude and 60° latitude

Front 20

The intertropical convergence zone (ITCZ) is a region where the...

Back 20

northeast trades meet the southeast trades

Front 21

On an upper air map, ridges are...

Back 21

elongated areas of high heights.

Front 22

El Niño events are marked by...

Back 22

higher than normal ocean temperatures over the eastern tropical Pacific.

Front 23

The most likely origin of mP (maritime polar) air masses that enter the western U.S. is

Back 23

the northern Pacific Ocean

Front 24

On a surface weather map, this marks the boundary where a cold, dry air mass encounters a warm, moist air mass.

Back 24

Cold front

Front 25

Why do we usually expect to find clouds and precipitation associated with low pressure areas, and clear skies and no precipitation associated with high pressure areas?

Back 25

Because rising air is present in areas of low pressure while in high pressure areas, sinking air occurs--which doesn't produce much cloud formation.

Front 26

During the ice crystal process of precipitation, ice crystals grow ________ while the surrounding liquid droplets get ________.

Back 26

larger; smaller

Front 27

Particles that serve as surfaces on which water vapor may condense is called...

Back 27

condensation nuclei

Front 28

In middle and high latitudes, the [most] effective method of precipitation formation is...

Back 28

the ice crystal process

Front 29

Cloud seeding is designed to trigger which precipitation forming process?

Back 29

the ice crystal process

Front 30

In the winter, you read in the newspaper that a large section of the Midwest is without power due to downed power lines. Which form of precipitation most likely produced this situation?

Back 30

freezing rain

Front 31

Radar gathers information about precipitation in clouds by measuring the

Back 31

amount of energy reflected back to the radar unit.

Front 32

Satellite images of clouds at night use...

Back 32

emitted infrared radiation.

Front 33

To correctly monitor horizontal changes in air pressure, the most important correction for atmospheric pressure measurements at the earth's surface is ________.

Back 33

altitude

Front 34

The amount of pressure change that occurs over a given horizontal difference is called the ________ ________.

Back 34

pressure gradient.

Front 35

The hydrostatic equation describes the equilibrium between the ________ and ________.

Back 35

vertical pressure gradient force; gravity

Front 36

Two places at the same elevation have the same sea level pressure. But at station A, the surface temperature is 8°C while at station B, the surface temperature is 18°C. If all other things remain constant, at 1000 meters above the surface, the pressure at station A would be ________ than the pressure at station B.

Back 36

less

Front 37

The contour lines drawn on a 500mb map are lines of constant ________.

Back 37

height

Front 38

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

Back 38

at all places on earth

Front 39

A wind that blows at a constant speed parallel to straight isobars is called a ________ ________.

Back 39

geostrophic wind

Front 40

What produces the strongest Coriolis force?

Back 40

Fast winds & high latitudes

Front 41

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

Back 41

rising; sinking

Front 42

On an upper-level map (such as a 500mb map) the wind tends to blow...

Back 42

parallel to the contour lines (whether curved or straight)

Front 43

In summer, where would you expect to find semipermanent high pressure areas?

Back 43

Over the ocean, because the ocean tends to be cooler than the land at this time of year.

Front 44

In the three-cell model of the general circulation, areas of surface high pressure should be found near...

Back 44

30° latitude and the poles

Front 45

In Honolulu, Hawaii (latitude 21°N), you would expect the prevailing winds to be from the _______.

Back 45

northeast

Front 46

The polar jet stream flows...

Back 46

in a wavy pattern from west to east.

Front 47

The most likely origin of mT (maritime tropical) air masses that enter the central U.S. is...

Back 47

the Gulf of Mexico

Front 48

On a surface weather map, the transition zone between two air passes with different temperature and moisture characteristics is marked by a ______.

Back 48

front

Front 49

A warm front is expected to pass Minneapolis-St.Paul by tomorrow. What is the most likely weather forecast for tomorrow?

Back 49

Wind from the south, rising temperatures and increasing humidity.

Front 50

This is a middle level cloud that spreads across the sky as a sheet.

Back 50

Altostratus

Front 51

A high, thin, "feathery" cloud.

Back 51

Cirrus

Front 52

An artificial cloud.

Back 52

Contrail

Front 53

A low cloud that is associated with steady precipitation.

Back 53

Nimbostratus

Front 54

A very tall cloud that is producing thunder and lightning.

Back 54

Cumulonimbus

Front 55

A halo often is associated with this cloud.

Back 55

Cirrostratus

Front 56

Which force causes surface winds to spiral toward the center of low pressure, but becomes insignificant as we move away from the earth's surface?

Back 56

Friction

Front 57

Which force initially causes the winds to blow?

Back 57

Pressure gradient force

Front 58

Which force depends on the speed of the earth's rotation?

Back 58

Coriolis force

Front 59

The warm sector of an extratropical cyclone is located ______________.

Back 59

ahead of a cold front

Front 60

Vorticity refers to ______.

Back 60

the spin of air parcels

Front 61

If the flow of air into a surface low pressure area is greater than the divergence of air above the low, the surface pressure in the center of the low will ______.

Back 61

increase

Front 62

A surface high pressure system typically is located _________.

Back 62

east of an upper-level ridge

Front 63

Developing high pressure areas generally have ______ air near the surface and ______ air aloft.

Back 63

diverging; converging

Front 64

The most likely time for ordinary thunderstorms to occur is ______.

Back 64

in the afternoon

Front 65

What is a line of severe thunderstorms called?

Back 65

Squall line

Front 66

Squall lines often form ahead of ______ ______.

Back 66

cold fronts

Front 67

Which is NOT associated with the formation of a hurricane?

• an area of low pressure
• location on the equator
• very warm sea surface temperature
• release of latent heat in tall cumulus clouds

Back 67

location on the equator

Front 68

Which area in the U.S. would most likely experience thunderstorms, hurricanes and tornadoes during the course of one year?

Back 68

The Gulf Coast States

Front 69

The forecasting technique that produces several versions of a forecast, each beginning with slightly different initial weather conditions to reflect uncertainty in the measurements is called...

Back 69

Ensemble forecasting

Front 70

At 9a.m. a warm front was approaching the Twin Cities from the southwest. The front is expected to reach northwestern Wisconsin by 6p.m. What is the most likely weather forecast for the Twin Cities on this day?

• Southeasterly winds shifting to southwesterly this afternoon, rising temperatures and decreasing dew points.
• Rising temperatures and nearly steady dew points this afternoon, with winds remaining calm throughout the day.
• Southeasterly winds shifting to southwesterly this afternoon, accompanied by rising temperatures and increasing humidity.
• Southwesterly winds shifting to northwesterly this afternoon, falling temperatures and decreasing dew points.

Back 70

Southeasterly winds shifting to southwesterly this afternoon, accompanied by rising temperatures and increasing humidity.

Front 71

A large circular high pressure area is located just west of the Twin Cities. The winds are from the north-northwest, skies are clear and there is low humidity. The center of high pressure is forecast to be located over southern Wisconsin by tomorrow. What is the BEST estimate of tomorrow's weather in the Twin Cities?

• Southerly winds, scattered cirrus clouds, and falling pressure.
• Easterly winds with a thin cirrostratus overcast and rising pressure.
• Northerly winds, low overcast with steady precipitation, and falling pressure.
• Westerly winds, overcast skies, and falling pressure.
• Southerly winds, clear skies, and rising pressure.

Back 71

Southerly winds, scattered cirrus clouds, and falling pressure.

Front 72

Why does Florida have a high frequency of thunderstorms?

Back 72

The rising air on land is replaced by the saturated air from the ocean. The lifted latent heat produces atmospheric instability and clouds/precip.

Front 73

A cold front is directly to the west of the Twin Cities and is moving east. What are the most likely changes you would expect in temperature, dew point, and wind direction from before the front arrives to after the front passes you?

Back 73

Winds will be variable as the front arrives as temperature and dew point will decrease quickly. Once it passes, the winds would be blowing to the north/northwest and the dew point will remain low and the temperature would be cool.

Front 74

A warm front is southwest of the Twin Cities and is moving toward the northeast. What are the most likely changes you would expect in temperature, dew point, and wind direction from before the front arrives to after the front passes you?

Back 74

Temperature and dew point would steadily increase, and winds will be light but variable. After, dew point will be higher with higher temperature, while winds would have hardly changed from prior to this warm front.

Front 75

What are long-range outlooks based on?

Back 75

Unlike forecasts, they are entirely based on a combination of modeling and statistics--may range for up to 3 months.

Front 76

What are the three resources referred to in making a thorough forecast?

Back 76

500mb map forecasts, sea-level pressure forecasts, and precipitation forecasts

Front 77

List and describe the four stages of the Polar Front Theory.

Back 77

1. Cyclonic wind shear across polar front.
2. Front kinks out and wave begins to develop.
3. "Open-wave" stage
• Precipitation from invading up along the warm front, with uplift along cold front
4. Occluded stage
• cold front merges with warm front
• widespread cloud cover and precipitation
• beginning of the end of the cyclone
• reduced latent heat release when all warm air is aloft
• reduced temperature contrast across occlusion

Front 78

At the SURFACE, air is ________ near the center of low pressure and _______ near the center of high pressure.

Back 78

converging; diverging

Front 79

For surface lows to persist, how do you get the necessary divergence aloft?

Back 79

1. Divergence due to differences in speeds
2. Difluence where contours get far apart

Front 80

for surface highs to persist, how is the convergence aloft sustained?

Back 80

1. Convergence due to differences in speed
2. Confluence where contours are closer together

Front 81

In the Northern Hemisphere: _______ vorticity refers to a counterclockwise spin and _______ vorticity refers to a clockwise spin.

Back 81

positive; negative

Front 82

A ____________ of upper-level troughs and ridges is the most favorable setting for the development of surface highs and lows.

Back 82

westward tilt with height

Front 83

What is cyclogenesis?

Back 83

The development of cyclones.

Front 84

Cold temperature advection occurs where the contours _____ the isotherms, and wind blows _____ air toward _____ areas.

Back 84

cross; cold; warm

Front 85

Warm temperature advection occurs where the _____ cross the isotherms and wind blows _____ air toward _____ areas.

Back 85

cross; warm; cold

Front 86

No temperature advection occurs where isotherms and contours are _______ to each other.

Back 86

Parallel

Front 87

The warm conveyor belt brings moist, warm surface air from the _____ toward the center of the low, rising up from the ________ and creating clouds and precip.

Back 87

south; warm frontal surface

Front 88

The cold conveyor belt brings cool (or cold) air from the _____ toward the center of the low, gaining moisture from the precip falling from the ______ above it.

Back 88

east; warm belt

Front 89

The dry conveyor belt brings very cold (thus--very dry) air from the ____ or _____ that spirals toward the center of the low, often creating a distinct dry slot behind the _______.

Back 89

north; west; cold front

Front 90

List and describe the three stages of a thunderstorm.

Back 90

• Cumulus Stage
- No precip, lightning or thunder.
- Warm, humid air rises and releases latent heat
- Strong updraft near center of cloud
- Water droplets and ice crytals together near cloud top
• Mature stage
- Heavy precip, decreasing intensity of lightning and thunder
- Precip particles are heavy enough to fall to ground
- Warm updraft, cold downdraft (gust front)
- turbulence near updraft/downdraft boundary can sometimes produce small hail
• Dissipating stage
- Light precip, decreasing intensity of lightning and thunder
- Updraft weakens
- Falling precip induces downdraft throughout the cloud
- High, anvil part of cloud may persist after bottom of cloud evaporates

Front 91

How do clouds become electrified (lightning is produced)?

Back 91

Electrification results from having both ice crystals and water droplets within the same cloud--or so it is believed so far.

Front 92

What is thunder?

Back 92

A shockwave we hear when air expands from the intense heating caused by lightning.

Front 93

What are the characteristics of ordinary thunderstorms?

Back 93

Short-lived (1 hr or less), small size (10 km/6 mi or smaller); produced by either unequal heating of earth's surface (thermals), orographic lifting, regions of rising air (low pressure center, sea breeze). Usually do not produce hail or strong winds. Daytime heating may also induce thunderstorms.

Front 94

What are the characteristics of supercell thunderstorms?

Back 94

Very large (25 mi/50 km diameter). Rotating updraft. gust front, rain, hail, possible tornado, hook echo.

Front 95

Describe the characteristics of tornadoes.

Back 95

Short-lived (10 minutes or last, but may persist). Short path length (track usually 4 miles or less). There are exceptions. Form in hook echo. Most frequent during late spring and early summer, but may occur any time of the year. EF0-EF5.

Front 96

Describe the theory of tornado formation.

Back 96

Tornadoes can form from the rotating updraft of a supercell thunderstorm, where the vertical wind shear induces rotation along the horizontal axis -- in which the strong updraft lifts the rotation and creates the rotation.

NEED: Strong air mass contrasts and vertical wind shear.

Front 97

Describe the organization formation of a hurricane.

Back 97

Near the ITCZ when it's away from the equator with an easterly (tropical) wave along a midlatitude frontal boundary that moves over warm, subtropical ocean water. Can be 400 miles in diameter and last about a week (there are exceptions).

Front 98

Describe the stages of hurricane development.

Back 98

1. Tropical disturbance
• Mass of thunderstorms with little circulation
2. Tropical depression
• Organized circulation develops, at least one isobar closed within the system. Wind speed <34 knots.
3. Tropical storm
• Organized circulation persists, decreased central pressure with several closed isobars. Wind speeds >34 but <64 knots.
4. Hurricane
• Well-organized circulation with distinct eye and spiral bands. Decreased central pressure with many closed isobars. Wind speeds >64 knots. Intensity categorized on Saffir-Simpson scale.

Front 99

What are the necessary conditions for hurricane development?

Back 99

Warm ocean water, position away from the equator (coriolis force needs to induce cyclonic circulation), and light winds/weak vertical wind shear (which allows energy released by condensation to remain within the developing storm).

Front 100

If the environmental lapse rate for a given layer of the atmosphere is greater than both the dry and wet adiabatic lapse rates i.e. the temperature DECREASES more RAPIDLY with height) then the atmospheric layer is called...

Back 100

Absolutely unstable

Front 101

If the environmental lapse rate is less than both the dry and wet adiabatic lapse rates (i.e.the temperature decreases LESS RAPIDLY with height), then the layer is termed...

Back 101

Absolutely stable

Front 102

If the environmental lapse rate is between the dry rate and the wet rates, then the atmospheric layer is called...

Back 102

Conditionally unstable