METEOROLOGY FINAL
Surface weather information is provided by more than ____ land-based stations and hundreds of ships and buoys providing surface weather information at least four times a day.
10,000
Each year, U.S. fire departments respond to more than ____ fires started by lightning in the United States.
20,000
How hot is lightning?
34,000 CELSIUS (54,000 FAHRENHEIT)
climatalogy
A forecast based on the climate of a particular region
Dissipating stage (thunderstorm)
After the storm enters the mature stage, it begins to dissipate in about 15 to 30 minutes. The dissipating stage occurs when the updrafts weaken as the gust front moves away from the storm and no longer enhances the updrafts.
A forecast method that compares past weather maps and weather patterns to those of the present is
Analogue method
Which of the following doesn't qualify as severe weather?
Continuous lightning
The first stage of a tornado life cycle is the ____ stage.
Dust whirl
According to the Enhanced Fujita Scale, an ____ tornado causes only minimal damage, whereas an ____ completely demolishes a house and sweeps it off its foundation.
EF-0; EF-5
Doppler radar is helpful for measuring precipitation, but not wind.
False
Is this statement true or false: "Lightning never strikes twice in the same place"?
False
Opening windows during a tornado decreases the pressure on the opposite wall and therefore decreases the chances that the building will collapse.
False
Scientists understand with certainty how clouds are electrified.
False
Seasonal forecasts make specific predictions of rain or snow. (In this case, specific refers to exact amounts of rain/snow and on what dates)
False
Thunderstorms are a common phenomenon in areas dominated by subtropical highs.
False
Weather technology has improved so much that a meteorologist can now accurately predict the precise location a tornado will form up to 7 days in advance.
False
Floods that develop rapidly with little or no advance warning are called ____ floods.
Flash
Which severe weather event kills more people than any other annually?
Flash-flooding
GFS
Global Forecast System
Wall cloud
If humid low-level air is drawn into the updraft, a rotating cloud may descend from the base of the storm.
Multicell thunderstorm
In a region where there is strong vertical wind shear (speed and/or directional shear), the thunderstorm may form in such a way that the outflow of cold air from the downdraft never undercuts the updraft. In such a storm, the wind shear may be so strong as to create horizontal spin, which, when tilted into the updraft, causes it to rotate. An intense, long-lasting thunderstorm with a single violently rotating updraft is called a supercell.
____________________ are placed on buildings to protect them from lightning damage.
Lightning rods
Modern computer forecasting models have increasingly smaller grid spacing. This presents which of the following problems?
Many more computations are needed.
Violent tornadoes (with winds exceeding 180 knots) that contain smaller whirls rotating within them are called ____.
Multi-vortex tornadoes
By definition, a "shelf cloud" is almost always ________, but will usually form at the leading edge of a ___________.
Nonsevere; thunderstorm
NAM
North American Mesoscale
There are many techniques involved in creating a weather forecast. Which of the following do not belong?
Numerical Modeling, Persistence, Farmer's Almanac
Which forecasting method assumes that weather systems will move in the same direction and at the same speed as they have been moving?
Persistence Forecast
What do the reflectivity colors show?
Precipitation, the stronger the returned precipitation, the heavier the energy?
What is weather forecasting?
Predicting how the present state of the atmosphere will change over time.
RUC
Rapid Update Cycle
How do lightning happen, cap'n?
Separate regions containing opposite electrical charges must exist within a cumulonimbus cloud
In the United States, tornadoes are most frequent during the ____, and least frequent during the ____.
Spring; winter
What is the most dangerous type of thunderstorm?
Supercell thunderstorm
A thunderstorm is a storm containing ____________________ and ____________________.
Thunder; lightning
A(n) ___________ is an intense rotating column of air that extends downward from the base of a thunderstorm with a circulation reaching the ground.
Tornado
Tornadoes have a distinct signature on the radar screen, known as the ____________________, which shows up as a region of rapidly (or abruptly) changing wind directions within the mesocyclone
Tornado Vortex Signature
Which is worse: tornado watch or warning?
Tornado warning
An anticyclone is moving slowly eastward. Southerly winds on the western side of the system will bring warmer and more humid air to the region. Therefore, afternoon temperatures will be warmer than those of the day before.
True
Sinking air warms, yet the downdrafts in a thunderstorm are usually cold.
True
The ASOS system is designed to provide nearly continuous information about wind, temperature, pressure, cloud-base height, and runway visibility at various airports.
True
Tornado frequency is highest during the spring and lowest during the winter when the warm surface air is normally absent.
True
Tornadoes have occurred in every state, including Alaska and Hawaii.
True
Lightning may occur from one cloud to another.
True.
A(n) ____ atmosphere is essential for tornado development.
Unstable
Decay stage
Usually finds the tornado stretched into the shape of a rope. becomes greatly contorted
Most often, tornadoes form with supercell thunderstorms in an environment with strong ____.
Vertical wind sheer
WRF
Weather Research and Forecast Model
What do the velocity colors show?
Wind speed, etc. red means winds blowing away, green means blowing towards
persistence forecast
a prediction that future weather will be the same as present weather
HP Supercell
a supercell dominated by heavy precipitation, strong downdrafts (downbursts), and large hail. Tornadoes wrapped in this may be difficult to see.
Funnel cloud
a tornado that is beginning to form but whose circulation has not reached the ground. Perhaps only about 30 percent of funnel clouds become active tornadoes. When viewed from above, the majority of North American tornadoes rotate counterclockwise about their central core of low pressure. Some have been seen rotating clockwise, but those are infrequent.
Tornadoes are usually observed
ahead of cold fronts.
Mature stage (thunderstorm)
appearance of downdraft marks beginning, most intense part of storm, updraft and downdraft now constitute the cell. Lightning and thunder present.
Cumulus stage
as a parcel of warm, humid air rises, it cools and condenses into a single cumulus cloud. As the cloud builds, the transformation of water vapor into liquid or solid cloud particles releases large quantities of latent heat, a process that keeps the rising air inside the cloud warmer (less dense) than the air surrounding it. The cloud continues to grow in the unstable atmosphere as long as it is constantly fed by rising air from below. Insufficient time for precipitation, typically. No lightning / thunder during this stage.
Bow echo
as strong winds rush forwards along the ground, they sometimes push the squall line outward so that it appears as a bow or a series of bows on a radar screen
Microburst
beneath an intense thunderstorm, the downdraft may become so localized so that it hits the ground and spreads horizontally in a radial burst of wind. can induce damaging straight-line winds well over 100 knots. damaging to aviation. come from virga.
Shrinking stage
characterized by an overall decrease in the funnel's width, an increase in the funnel's tilt, and a narrowing of the damage swath at the surface, although the tornado may still be capable of intense and sometimes violent damage.
Numerical prediction
computers on Earth are devoted to weather and climate prediction. The routine daily forecasting of weather by computers using mathematical equations
multicell thunderstorm
contain a number of cells, each in a different stage of development; tend to form in areas of moderate to strong vertical wind shear; this type of shearing causes the cell inside the storm to tilt in such a way that the updraft actually rides up and over the downdraft. Notice also that precipitation inside the storm does not fall into the updraft (as it does in the ordinary cell thunderstorm), so the storm's fuel supply is not cut off and the storm complex can survive for a long time. Long-lasting multicell storms can become intense and produce severe weather for brief periods.
Mature stage
damage normally is most severe as the funnel reaches its greatest width and is almost vertical. when a tornado reaches its mature stage, its circulation usually stays in contact with the ground until it dissipates.
Heat lightning
distant lightning from thunderstorms that is seen but not heard, frequently appears on hot summer nights when the overhead sky is clear
mesoscale convective systems
driven by convective processes and because they are mesoscale (middle scale) in size. organized thunderstorms that can take on a variety of configurations
Dust-whirl stage
dust swirling upward from the surface marks the tornado's circulation on the ground and a short funnel often extends downward from the thunderstorm's base
Sheet lightning
forms when either the lightning flash occurs inside a cloud or intervening clouds obscure the flash, such that a portion of the cloud appears as a luminous white sheet, eh?
Ribbon lightning
forms when wind moves the ionized channel between each return stroke, causing the lightning to appear like it's hanging from the cloud
Supercell thunderstorms are different from ordinary thunderstorms in that supercell thunderstorms
have a tilted, rotating updraft in the mature stage.
Ordinary cell thunderstorms most frequently form
in the afternoon
Ball lightning
looks like a luminous sphere, often about the size of a football, appears to float in the air or slowly dart about for several seconds
Many flash floods, including the one that occurred in Colorado's Big Thompson Canyon, are the result of thunderstorms that
move slowly
Squall line
multicell thunderstorms may form as a line of thunderstorms. form directly along a cold front and extend for hundreds of miles, or the storm may form in the warm air 100 to 300KM ahead of the cold front
The forecasting of weather by a computer is known as
numerical weather prediction.
What would be the least accurate forecast method of predicting the weather two days into the future during changeable weather conditions?
persistence forecast
Analogue method
relies on the fact that existing features on a weather chart (or a series of charts) may strongly resemble features that produced certain weather conditions sometime in the past. To the forecaster, the weather map "looks familiar." pattern recognition
Mesocyclone (the rotating updraft)
rotating air column on the south side of the storm, usually 5 to 10 kilometers across, so strong that precipitation cannot fall through it. This situation produces a rain-free area (called a rain-free base) beneath the updraft. Strong southwesterly winds aloft typically blow the precipitation northeastward
Ordinary ("Pop-Up") T-Storm
scattered thunderstorms, typically form on warm humid days, tend to form in warm, humid air masses away from significant weather fronts. These thunderstorms can be considered "simple storms" because they rarely become severe, typically are less than a kilometer wide, and they go through a rather predictable life cycle from birth to maturity to decay that usually takes less than an hour to complete. Limited vertical wind shear.
An ensemble forecast goes further and further into the future, the forecast lines can become scrambled. Such a chart is often referred to as a
spaghetti plot.
Derecho
straight-line winds gusting to more than 50 knots (58 mi/hr) persist along a path at least 400 km (250 mi) long, However, with a derecho, debris is blown in one direction and generally over a wide area, whereas debris with a tornado is usually thrown in many directions.
Trend method
surface weather systems tend to move in the same direction and at approximately the same speed as they have been moving, providing no evidence exists to indicate otherwise
LP Supercell
tend to produce little rain, they are still capable of producing large hail as well as tornadoes. The rotation is often visible in a bell-shaped central tower, with a corkscrew-like pattern along its sides. Tornadoes are clear and visible
No country experiences more tornadoes than ____.
the United States
organizing stage
the tornado increases in intensity with an overall downward extent of the funnel
When a large number of tornadoes develop in association with a particular weather system (typically six tornadoes or more), it is referred to as a ____.
tornado outbreak
A tornado ___________ is issued once a tornado is spotted, either visually or on a radar screen.
warning
About 70 percent of all tornadoes in the United States develop from ____.
March to July
A weather watch would probably be issued for which of the following conditions?
There is a chance for tornadoes this afternoon/evening.
Squall line thunderstorms generally form
along or ahead of a cold front.
When caught in a thunderstorm in an open field, the best thing to do is to
crouch down as low as possible while minimizing contact with the ground.
The forecasting technique that produces several versions of a forecast model, each beginning with slightly different weather information to reflect errors in the measurements, is called
ensemble forecasting
A weather warning indicates that
hazardous weather is either imminent or occurring within the forecast area
An ordinary thunderstorm
is a scattered/isolated storm and normally not severe.
For ____ to occur, separate regions containing opposite electrical charges must exist within a cumulonimbus cloud.
lightning
The tornado alley of the United States ____.
stretches from central Texas to Nebraska
During the summer, what conditions prevail near the surface over the Great Plains that help a hailstone survive as ice all the way to the ground?
strong updrafts
Supercell thunderstorms differ from ordinary cell (air mass) thunderstorms because
the updraft in a supercell thunderstorm is longer-lasting and rotates.