Exam 3 Flashcards
In numerical weather prediction, forecast and errors may come from errors in ________ and ________.
Initial condition; model
Three stages of an ordinary cell thunderstorm.
- Cumulus stage
- Mature stage
- Dissipating stage
What happens to the warmer air mass when it collided with a colder air mass?
Forced to lift
The difference of a hurricane and a mid-latitude cyclone in the core, in terms of temperature and motion are:
Cold updraft in mid latitude cyclone, warm downdraft in hurricane
What type of clouds (in order) would you see
Cirrus, cirrostratus, altostratus, nimbostratus
Six steps of mid-latitude cyclones development based on the Polar Front Theory.
- Stationary front
- Frontal wave
- Open wave
- Initial occlusion
- Advanced occlusion
- Cut off cyclone
What happens to a surface low of an upper air low lies directly above it?
Weakens
On a weather map, the transition zone between two air masses with sharply contrasting properties is marked by
A front
The development or strengthening of a middle latitude cyclone storm system
Cyclogenesis
The rising of warm air up and over cold air
Overrunning
An air mass is characterized by similar properties of ________ and ________ in any horizontal direction.
Temperature; moisture
For cyclogenesis to occur along a frontal wave, the winds aloft directly above the wave should be
Diverging
Atmospheric short waves usually move _____to_____ at a speed that is ________ than longwaves.
West to east; faster
According to the model of the life cycle of a wave cyclone, the storm system is normally most intense
When the system first becomes occluded.
What type of air mass would be responsible for hot, dry summer weather in southern Arizona? (c/m and T/P)
cT
A stationary front does not move because
The winds blow parallel to the front
Developing low pressure areas generally have ________ air near the surface and ________ air aloft.
Converging; diverging
Which of the following is not correct concerning a warm front?
It has warm air ahead (in advance) of it.
One would expect a cP air mass to be
Cold and dry.
What type of air mass would be responsible for snow showers on the western slopes of the Rockies?
mP
When an upper-level low lies directly above a surface low:
The surface low will probably weaken.
A true cold front on a weather map is always
Followed by cooler air.
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
What type of weather front would be responsible for the following weather forecast: “increasing cloudiness and warm today with the possibility of showers by this evening, turning much colder tonight, with winds southwesterly becoming gusty and shifting to northwesterly by tonight”?
Cold front
A good source region for an air mass would be
Generally flat areas of uniform composition with light surface winds
When comparing an “average” cold front to an “average” warm front, which of the following is not correct?
Generally, precipitation covers a much broader area with a cold front
In the polar front theory of a developing wave cyclones energy for the storm is usually derived from all but one of the following:
Heat energy stored in the ground
The type of weather system known as a “mid latitude cyclone” cannot form over the tropical ocean because
Surface temperatures contrasts are not large and the Coriolis force is weak in the tropics.
What type of weather front would be responsible for the following weather forest: “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
For a surface storm system to intensify, the upper-level low (or trough) should be located to the _____ of the surface low.
West
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, nimbostratus
The greatest contrast in both temperature and moisture will occur along the boundary separating which air masses?
mT and cP
A warm, moist air mass that forms over water is called
mT
When two air masses collide at a front, one air mass is pushed upward by the other. This is because
One air mass is denser than the other
Before the passage of a cold front, the pressure normally _____, and after the passage of a cold front, the pressure normally _____.
Drops; rises
Lake-effect snows are best developed around the Great Lakes during
Late fall and early winter when cold, dry polar air moves over the relatively warm water
Which of the following is not correct concerning a cold front?
It is colored purple on a weather map.
Suppose that where you live in the middle of January is typically several degrees warmer than the rest of the month. If you forecast this January thaw for the middle of next January, you would have made a
Climatological forecast
Which of the following explain why it is possible to see clouds on satellite photos taken at night?
The clouds emit infrared light
The greatest improvement and forecasting skill during the past decade has been
In the lead time for watches and warnings of severe storms.
Weather forecast predicts that the future weather will be the same as the present weather is called
A persistence forecast
A weather warning indicates that
Hazardous weather is either imminent or occurring within the forecast area
An accurate forecast
May or may not show skill.
What position would you expect to hear the following 12 hour forecast: “cloudy and cold this morning with snow this afternoon and tonight”? (MLC)
Above the mid-latitude cyclone (triangular) tip
A polar orbiting satellite would provide a more detailed view of a severe thunderstorm than a geosynchronous satellite.
True
A weather forecast for the immediate future that employs the trend messages is called
Nowcasting
The forecast method that compares past weather maps and weather patterns to those of the present is
The analogue method
By examining the surface map, the movement of a surface low-pressure area can be predicted based upon the
All of the above
A forecaster will use a prognostic chart for guidance in preparing a forecast, but will also rely on personal experience and the knowledge of local features that can affect the weather.
True
Which of the following would probably be used to infer cloud altitude on a satellite photograph?
Intensity of infrared emissions
Bright white on an infrared cloud picture indicates
A cold, high altitude cloud
The forecasting technique that produces several version of a forecast model, each beginning with slight different weather information to reflect errors in the measurements is called
Ensemble forecasting
A prog is
A forecast chart that shows the atmosphere at some future time
Satellites can observe the movement of the air in areas where there are no clouds by detecting IR radiation emitted by water vapor.
True
An analysis is
A surface or upper-level chart that depicts the present weather patterns
A weather watch would probably be issued for which of the following conditions?
There is a chance for tornadoes tomorrow.
Which of the positions on a mid latitude cyclone diagram would you expect to hear the following 12 hour forecast: “cloudy with possible showers today, turning colder by tonight”?
Inside of the triangular shape, right before the cold front hits
The storm system MLC will apparently move toward the
Northeast
Which forecasting method assumes that weather systems will move in the same direction and at the same speed as they have been moving?
Steady state (trend) forecast
Which of the positions on a mid latitude cyclone diagram would you expect to hear the following 12 hour forecast: “partly cloudy and continued form through this afternoon and evening”?
Inside of the triangle, right after the warm front
Which of the positions on a mid latitude cyclone diagram would you expect to hear the following 12 hour forecast: “clearing and colder today with continued rising pressures”?
Just after the cold front
The forecasting of weather by a computer is known as
Numerical weather prediction
Which of the following is presently a problem with modern-day weather predictions?
All of the above
A probability forecast that calls for a 40% chance of rain means that
There is a 40% chance that any random place in the forecast area will receive measurable rain.
Which of the following is true of geosynchronous satellites?
They orbit the earth once a day
A tall cumulonimbus cloud would appear _____ on a visible satellite and _____ on an infrared cloud picture.
White; white
Weather observations made by most countries of the world are shared and distributed globally by international agencies.
True
A relatively narrow down burst, less than 4 km wide, is called
A microburst
A small thunderstorm cloud with virga falling out of its base and blowing dust at the ground could warn of a severe hazard to aircraft because
This could indicate an intense downdraft or microburst
Different tornadoes spawned by the same thunderstorms are said to occur
In families
On the surface weather map, this marks the boundary where a warm, dry air mass encounters a warm, moist air mass.
Dryline
A hook shaped echo on a radar screen often indicates that
The possible presence of a tornado producing thunderstorm
The so-called tornado belt of the United States is located
In the central Plains
What would be the proper sequence of events in a lightning flash?
Stepped leader, return stroke, dart leader, return stroke
The leading edge of the thunderstorms cold downdraft is known as
Gust front
A line of thunderstorms that forms the head of and advancing cold front is called
Squall line
The rotating up draft inside a severe thunderstorm is called
Mesocyclone
A group of thunderstorms which developed in a line one next to the other, each in a different stage of development, are called
Multi cell thunderstorm
Downdraft spread through a thunderstorm during the ________ stage.
Dissipating
The initial stage of an ordinary cell thunderstorm is the
Cumulus stage
If you see a lightning stroke and then, 15 seconds later, hear the thunder, the lightning is about _____ miles away.
3
Thunder is caused by
The rapid heating of air surrounding the lightning channel
Measures the speed at which precipitation is moving toward or away from an observer
Doppler radar
On the Doppler radar screen, a tornado might appear as
A region of rapidly changing windspeeds
The most likely time for an ordinary cell thunderstorm to form is
Late afternoon
The top of a thunderstorm is normally ________ charged, and the middle and lower parts are ________ charged.
Positively; negatively
In the cloud to ground lightning, the stepped leader travels ________ and the return stroke travels ________.
Downward; upward
A supercell storm is
And enormous thunderstorm that lasts for several hours
The Fujita scale pertains to
The strength of a tornado
You are generally safe inside an automobile during a lightning storm because
The metal car body will carry the lightning current around the passengers inside
In a region where severe thunderstorms with tornadoes are forming, one would not expect to observe
A strong ridge of high-pressure over the region
Ordinary sell thunderstorms only last about one hour and begin to dissipate when
The downdraft spreads throughout the cloud and cuts off the updraft.
A Doppler radar determines precipitation ________ by measuring changes in the ________ of the reflected radio wave.
Velocity; frequency
Which of the following statements about tornadoes is correct?
The United States has more tornadoes than any other country in the world.
If a tornado is rotating in a counterclockwise direction and moving toward the Northeast, the strongest winds will be on its ________ side.
Southeastern
An ordinary so thunderstorm is most intense during the ________ stage.
Mature
Discharge of electricity from or within a thunderstorm is called
Lightning
The first three stages of developing hurricane are:
- Tropical disturbance
- Tropical depression
- Tropical storm
The vertical structure of the hurricane shows an upper-level ________ of air, and a surface ________ there.
Outflow; inflow
In the northern hemisphere, hurricanes and mid-latitude cyclones are similar in that both
Have winds that blow counterclockwise around their centers
Pressure at the center of the hurricane is ________ than the surroundings at the surface and ________ at the surroundings aloft.
Lower; higher
The main difference between a hurricane and a tropical storm is that
Wind speeds are greater in a hurricane
In a hurricane, the eye wall represents
A zone of intense thunderstorms around the center
The skies in the center (or eye) of a hurricane are often cloud free. This is because the air in the eye
Is sinking
Which statement below is not correct concerning hurricanes?
A hurricane moving northward over the pacific will normally survive for a longer time than one moving north over the Atlantic.
The main source of energy for a hurricane is the
Warm ocean water and release of latent by condensation
Hurricanes do not form
Along the equator.
Which forms only over water?
Hurricanes
Hurricanes dissipate when
All of the above
Which is not an atmospheric condition conductive to the formation of hurricanes?
Strong upper-level winds
Which would you not expect to observe as the eye of a hurricane passes directly over your area?
High winds
At the periphery of a hurricane the air is ________, and several kilometers above the surface, in the eye, the air is ________.
Sinking; sinking
Hurricanes can’t form along the equator because
The Coriolis force is too small along the equator.
A weak trough of low pressure found in the tropics and along which hurricanes occasionally form is called
An easterly wave
On the Saffir-Simpson hurricane scale, a hurricane with winds in excess of 155 miles an hour and a central pressure or 910 mb would be classified as a category _____ hurricane.
5
Storms that form in the tropics are given names when
They reach tropical storm strength
As a northward-moving hurricane passes to the east of an area, surface winds should change from
NE to N to NW
The strongest winds in a hurricane are found
In the eye wall
Suppose the eye of a hurricane passed directly over you, and you survived the experience. If winds were from the NE as the eyewall first approached you, from what direction did the winds blow when the eyewall reached you the second time?
SW
Which of the following is not true concerning an easterly wave?
Has converging winds on its western side
A tropical storm becomes a hurricane when
The winds exceed 64 knots (74 mph)
The term storm surge refers to
A rise in ocean level of several meters or more.
