Thunderstorms
Severe Weather
Tropical Storms
Recurring Weather
Vocab
100

What are the conditions needed for a thunderstorm’s cumulus stage?

Source of moisture , lifting of the air mass , and unstable atmosphere  


100

What are the characteristics of a severe storm?

• Continuous supply of surface moisture

• Upper-Level low pressure system causing unstable air

• Large temperature differences between air masses


100

Describe the major wind systems that guide a tropical cyclone as it moves from the tropics to the mid-latitudes.

Initially, move northwestward due to trade winds

Then, controlled by prevailing westerlies


100

How would relatively light rain potentially cause flooding?

If it rains for a long enough time the ground may become saturated, leading to excessive runoff and flooding.

100
What does the Windchill Index do?

It measures the wind chill factor, by estimating the heat loss from human skin caused by a combination of wind and cold air

200

How does a thunderstorm form along a front?

Results when cold air forces warm air to rapidly rise  (If the warm air is significantly warmer and has a large amount of moisture, then the storm will be larger)  


200

What are the two characteristics of thunderstorms that lead to hail formation?

1. Strong updrafts and downdrafts circulate the hailstone.

2. Liquid water in freezing parts of the cloud allows for adding layers to the hailstone.


200

What two conditions must exist for a tropical cyclone to form?

Warm ocean temperatures as a source of energy and disturbance in the atmosphere to provide unstable air (aka low pressure) 


200

Why is the air in a winter high-pressure system is very cold despite compressional warming?

Snow on the ground reflects sunlight so heat is not absorbed.

Low angle of sun means less concentrated light.

Clear skies means that there is not insulating blanket to retain heat.


200
What is the Eyewall?

The eyewall is a band immediately surrounding the eye that contains the strongest winds in a hurricane 

300

What is the difference between a sea-breeze thunderstorm and a mountain thunderstorm?

• Both are air mass thunderstorms; the storm occurs inside one air mass

• Mountain thunderstorm occurs as a result of orographic lifting

• Sea breeze thunderstorm occurs due to difference between land and ocean heating


300
Why can some hail become baseball-sized?

Strong updrafts and downdrafts keep the hailstone suspended, moving it up and down between freezing and liquid zone and layers of ice.

300
What causes a cyclone to dissipate? 

Moves over land or cold water

In both cases, it loses its source of energy, warm ocean water


300

Compare the data of the heat-index scale and the wind-chill index. What variables influence each scale?

Heat-Index – Temperature and Relative Humidity

Windchill – Temperature and Wind Speed


300
What is a Supercell?
A self-sustaining thunderstorm (known for its intense rotating updrafts)
400

What causes a thunderstorm to dissipate?

Convection cells exist as long as there is warm, moist air at Earth’s surface. Once down drafts begin, the updrafts slow and eventually stop, because of surface cooling.

400
What are the steps that change wind shear into a tornado?

1. Wind shear causes a “rolling pin” of wind over the surface.

2. Passing over a warm place leads to an updraft that turns the “rolling pin” from horizontal to vertical

3. The “rolling pin” stretches out and wind speeds increase to form a tornado


400

Imagine that you live on the eastern coast of the United States and are advised that the center of a hurricane is moving inland 70km north of your location. Would a storm surge be a major problem in your area? Why or why not?

No, low pressure hurricanes rotate CCW in the Northern hemisphere

So, storm surge would hit north of the eye


400

A storm stalls over Virginia, dropping 0.75 cm of rain per hour. If the storm lingers for 17 hours, how much rain will accumulate?

17hrs * 0.75 cm/hr

= 12.75 cm of rain

400
What is the definition for Stepped Leader? 

A channel of partially charged air.

500

What are the similarities and differences of how a cold front creates thunderstorms compared to how a warm front would?

Cold- Rapid uplift creates towering cumulonimbus, intense thunderstorm with concentrated precipitation

Warm- Gentle lifting creates wide spread stratus clouds that produce gentle and wide spread rain. Mild Thunderstorm


500
The Fujita Scale rates tornadoes based off of their?
It is based off of their wind speed and damage (over a small area)
500
The Saffir-Simpson Scale rates hurricanes off of their? 
It judges them off of their rate of wind, sea level change, and damage (over a large area) 
500
What is a drought?

It is an extended period of well-below-average rainfall, usually caused by shifts in global wind patterns

500

What is the definition for Return Stroke?

A branched channel of positively charged particles.

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