Tornadoes Flashcards
What is a tornado?
A tornado is a violently rotating column of air extending between a cloud and the surface of the earth.
Why do tornadoes account for a large number of fatalities as compared to other natty d’s?
Short warning times
Catastrophic nature of the damage
In general, the weakest tornadoes have the wind speed of a hurricane
Why are the amount of tornado related deaths generally decreasing?
Better education
Better construction practices
Better warning times and communication of warnings
Why do most of the world’s tornadoes tend to occur over North America?
Warm-moist air source
Cold air source
All significant mountain ranges are oriented north-south
What is tornado alley? Why do most tornado related death not occur in this area?
An area that includes most of the eastern U.S between Texas and florida, which has the highest frequency of interactions between warm and cold air masses. This causes many tornadoes.
Most deaths tend to occur in the deep south because of poorer warning systems.
Why do hurricane frequencies tend to peak in September, while tornado frequencies tend to peak in May?
Ocean temperatures are warmest in September, while thunderstorm activity tends to peak in may.
How do we measure the strength of a tornado?
By measuring the damage associated. To do so, we use the Fujita scale.
How do we detect a Tornado?
Through warning systems, such as doppler radars.
Also, there are storm spotters.
Tornado Ingredients
In order for tornadoes to form, you need a thunderstorm.
Thunderstorms form through (LIM)
- A source of moisture (water vapor): North America has a proximity to the Gulf of Mexico and to the Gulf stream current of the North Atlantic ocean
- A conditionally unstable atmosphere, which makes air particles less dense
- A mechanism to trigger a thunderstorm updraft, either through forced lifting or heating
What is a lapse rate?
the rate at which atmospheric temperature decreases with increase in altitude
Types of lifting mechanisms
Lifting by a front: lifting caused by warm air rising over cold air
Lifting by a gust: cold air outflow region lifts warm air
Lifting by sea breeze front: cold air over the ocean collides with warm air on land. The friction causes the warm air to rise over the cold air
Stages of a thunderstorm life cycle
- Cumulus (warm, buoyant plume with updrafts)
- Mature (combination of both updrafts and downdrafts)
- Dissipating (falling precipitation shuts off the updrafts…all downdrafts and system self destructs
Why do airmass thunderstorm rarely produce tornadoes? How can tornadoes form?
- Updrafts are suppressed by the weight of the water
- There is no inherent rotation to work with
However, both these liabilities can be overcome by wind shear. Wind speeds tend to increase with elevation, which creates a rotation. When vertical shear is introduced, the angle of rotation changes, and the updraft is removed from the area of precipitation. At this point, the thunderstorm is called a supercell.
Eventually a mesocyclone is formed.
What is the difference between a tornado warning and a tornado watch?
Tornado watch: Indicates that conditions are favorable for tornadoes to form. The watch may be given as much as 12 hours in advance of the potential event.
Tornado warning: This means that a tornado is believed to be present in the warning area.
Tornado safety measures
When a tornado watch is issued, listen to a weather radio, or use cell phone app
If at home, move to a designated shelter, such as a basement
If there is no basement, move to an interior room and avoid windows (put as many walls as possible between you and the tornado)
If outside, move to a low elevation away from any possible airborne object
