weather

WEATHER INTRODUCTION

This PowerPoint is designed to review different types of fronts and severe weather. Please view the PowerPoint in its entirety, as well as, completing the activity and quizzes, and viewing the simulation.

You may go back and review the PowerPoint at any time.

This is intended to help you with your Chapter 24 test.

TABLE OF CONTENTS

Fronts

Activity: Predicting the Weather

Quiz: Fronts

Severe Weather

Simulation: How Cumulus Clouds Form

Quiz: Severe Weather

WEATHER

According to Dictionary.com, weather is defined as “The state of the atmosphere at a given time and place, with respect to variables such as temperature, moisture, wind velocity, and barometric pressure.”

FRONTS

Density differences keep two air masses separate when they meet.

One air mass must collide with another air mass.

The kind of front that forms is determined by how the air masses move in relationship to each other.

TYPES OF FRONTS

Cold Front - The front edge of a moving mass of cold air that pushes beneath a warmer air mass like a wedge.

Warm Front – The front edge of advancing warm air mass that replaces colder air with warmer air.

Stationary Front – A front of air masses that moves either very slowly or not at all.

Occluded Front – A front that forms when a cold air mass overtakes a warm air mass and lifts the warm air mass off the ground and over another air mass.

SLOW MOVING COLD FRONT

Lifts warm air more slowly

Produces weaker storms

Produces lighter precipitation

FAST MOVING COLD FRONT

Clouds will form if the warm air is moist

Large cumulus and cumulonimbus clouds

Storms are usually short-lived and sometimes violent

Air behind cold front is noticeably colder and drier

WARM FRONT

Less dense warm air rises over the cooler air

Clouds may extend far ahead of the base of the front

Stratus clouds

Produces gentle precipitation over a large area

May cause violent weather

Air behind the warm front is warmer and more moist

COLD FRONT AND WARM FRONT

STATIONARY & OCCLUDED FRONTS

Stationary Front

Weather is similar to a warm front

Produces precipitation over a large area

May cause violent weather

Occluded Front

Wide variety of weather

Thunderstorms possible

Usually their passage is associated with a drying of the air mass

OCCLUDED FRONT

STATIONARY FRONT

PRACTICE PREDICTING THE WEATHER

Predict the WeatherDirections:1.) Click on the picture above2.) Once the webpage is open, click on “Predict the Weather”3.) Click on “Start Level 1”4.) Once you are finished with level one, bring me your computer so I can record your quiz score5.) Repeat for Levels 2 & 3

QUIZ: FRONTSCLICK ON THE CORRECT

ANSWER

1.) What is most likely to occur when a mass of cold air moves into a region occupied by warmer air?

A warm front will form, and there will be intense precipitation.

The air masses will mix rapidly, forming an air mass of intermediate temperature.

The boundary between the two air masses will be a zone of intense high pressure.

A cold front will form, as warm air is forced upward.

All of the above.

QUIZ: FRONTS

Sorry! Try Again.

QUIZ: FRONTS

GREAT JOB!

QUIZ: FRONTSCLICK ON THE CORRECT

ANSWER

2.) A front that is characterized by stratus clouds, and gentle precipitation for a long time is a(n) _______________ front.

cold

stationary

warm

occluded

none of the above

QUIZ: FRONTS

Sorry!Try Again.

QUIZ: FRONTS

Way to Go!

QUIZ: FRONTSCLICK ON THE CORRECT

ANSWER

3.) Storms along a cold front are usually short-lived and sometimes violent, while storms along a warm front

are short-lived and weak.

produce precipitation over a large area, and are sometimes violent.

are narrow, producing little rain and are always violent.

are long-lived, but always weak.

QUIZ: FRONTS

Sorry!Try Again.

QUIZ: FRONTS

Excellent!

QUIZ: FRONTSCLICK ON THE CORRECT

ANSWER

4.) A front that forms when a cold air mass overtakes a warm air mass and lifts the warm air mass off the ground and over another air mass is called a(n)

warm front.

stationary front.

occluded front.

cold front.

QUIZ: FRONTS

Sorry!Try Again

QUIZ: FRONTS

Super!

SEVERE WEATHER

Severe Weather – weather that may cause property damage or loss of life.

This type of weather causes billions in damage each year

Sever Weather may include:

Large quantities of rain

Lightning

Hail

Strong Winds

Tornadoes

THUNDERSTORMS

Thunderstorm – a heavy storm that is accompanied by rain, thunder, lightning, and strong winds.

Thunderstorms develop in 3 stages

Cumulus Stage – warm, moist air rises, and the water vapor within the air condenses to form a cumulus cloud

Mature Stage – condensation continues as the cloud rises and becomes a dark cumulonimbus cloud

Heavy, torrential rain and hailstones may fall

Strong updrafts continue to rise, downdrafts form as air is dragged downward by the falling precipitation

Dissipating Stage – strong downdrafts stop air currents from rising

Thunderstorm dissipates as the supply of water vapor decreases

THUNDERSTORM CONT.

LIGHTNING

When clouds discharge electricity

Clouds must have areas that carry distinct electrical charges

Upper part of the cloud usually carries a positive charge

Lower part of the cloud mainly carries a negative charge

A huge spark travels within the cloud or between the cloud and ground to equalize electrical charges

LIGHTNING CONT.

TORNADOES

Tornado – a destructive rotating column of air that has very high wind speeds and that is visible as a funnel-shaped cloud

This is the most violent, and shortest-lived severe storm

Forms when a thunderstorm meets high-altitude horizontal winds

Horizontal winds cause the rising air to rotate

A storm cloud may develop a narrow, funnel-shaped, rapidly spinning extension that reaches downward

TORNADOES CONT.

Tunnel will move in a wandering, haphazard path if it touches the ground

Generally covers paths not more than 100 m wide

Usually, everything in that path is destroyed

Destructive power of a tornado is mainly due to the speed of the winds in the funnel

Winds may reach speeds of more than 400 km/h

Most injuries and deaths caused by tornadoes occur when people are trapped in collapsing buildings or are struck by objects blown by the wind

TORNADOES CONT.

HURRICANES

Hurricane – a severe storm that develops over tropical oceans and whose strong winds of more then 120 km/h spiral in toward the intensely low-pressure storm center

Warm, moist air over the ocean rises rapidly

Fully developed hurricanes consist of a series of thick cumulonimbus cloud bands that spiral upward around the center of the storm

Winds increase toward the center, or eye, of the storm and reach speeds of up to 275 km/h along the eyewall

The eye itself is a region of calm, clear, sinking air

HURRICANES CONT.

About 700 km in diameter

Most destructive storms that occur on Earth

Most dangerous aspect is rising sea level and large waves, called a storm surge

Every hurricane is categorized on the Saffir-Simpson scale by using several factors

Central pressure

Wind speed

Storm surge

Category 1 storms = least damage

Category 5 storms = catastrophic damage

HURRICANES CONT.

HURRICANES CONT.

Click on the picture below to see how cumulus clouds form

QUIZ: SEVERE WEATHER

CLICK ON THE CORRECT ANSWER

1.) The eye of the hurricane is a region of

hailstorms.

torrential rainfall.

calm, clear air.

strong winds.

QUIZ: SEVERE WEATHER

Sorry! Try Again

QUIZ: SEVERE WEATHER

Exceptional!

QUIZ: SEVERE WEATHER

CLICK ON THE CORRECT ANSWER

2.) In the mature stage of a thunderstorm, a cumulus cloud grows until it becomes a

stratocumulus cloud.

altocumulus cloud.

cumulonimbus cloud.

cirrocumulus cloud.

QUIZ: SEVERE WEATHER

Sorry! Try Again

QUIZ: SEVERE WEATHER

Out of Sight!

QUIZ: SEVERE WEATHER

CLICK ON THE CORRECT ANSWER

3.) What type of path does a tornado take if it touches down?

haphazard

extremely wide

straight

predictable

QUIZ: SEVERE WEATHER

Sorry! Try Again

QUIZ: SEVERE WEATHER

Sensational!

QUIZ: SEVERE WEATHER

CLICK ON THE CORRECT ANSWER

4.) Lightning is caused by

heavy precipitation.

electrical differences within clouds or between the ground and a cloud.

thunder.

strong winds.

QUIZ: SEVERE WEATHER

Sorry! Try Again

QUIZ: SEVERE WEATHER

Stupendous!

REFERENCES

Allison, M. A., DeGaetano, A. T., Pasachoff, J. A. (2008). Earth Science. Holt, Rinehart and Winston.

Bell, J., Prawat, R., et. al. A realist-constructivist approach to weather. (23 Feb., 2005). Retrieved April 19, 2010 from http://www.mltoolbox.org/wx/

Dictionary.com. (2010). Retrieved April 17, 2010 from http://dictionary.reference.com/browse/weather

Freedom Communications, Inc. “Occluded front.” Image. (2010). Retrieved April 19, 2010 from http://www.cbs6albany.com/images/research/Occluded_Schematic.JPG

Geography for kids, the study of our earth. “Stationary front.” Image. (1998). Retrieved April 20, 2010 from http://www.kidsgeo.com/images/stationary-front_sm.jpg

“Hurricane.” Image. Retrieved April 19, 2010 from http://blog.lib.umn.edu/olso4158/architecture/katrina-hurricane-pic3%5B1%5D.jpg

Impact Lab. “Tornadoes.” Image. (8 April 2009). Retrieved April 20, 2010 from http://www.impactlab.com/wp-content/uploads/2009/04/tornado.JPG

Mudra, P. “Squall line.” Image. (2010). Retrieved April 20, 2010 from http://www.bom.gov.au/weather/wa/sevwx/sevtspd.jpg

REFERENCES CONT.

Short, N. M. “Warm front.” Image. (2010). Retrieved April 19, 2010 from http://www.fas.org/irp/imint/docs/rst/Sect14/warmfront.jpg

UCAR Communications. “Thunderstorm.” Image. 2002. Retrieved April 19, 2010 from http://www.ucar.edu/communications/newsreleases/2002/thunderstorm.jpg

Van Dam, J. “Lightning.” Image. (2 June 2008). Retrieved April 20, 2010 from http://www.myscience.nl/wp-content/gallery/lightning/800px-lightning_strike_jan_2007.jpg

“Warm and cold front.” Image. (2006). Retrieved April 19, 2010 from http://www.suu.edu/faculty/colberg/Hazards/Weather/fronts1.jpg

Wheatley, G. EdHeads. (2000). Retrieved April 19, 2010 from http://www.edheads.org/

Wikipedia. (2 April 2008). Retrieved April 20, 2010 from http://en.wikipedia.org/wiki/Weather_front

Wikipedia. “Cold front.” Image. (2 April 2008). Retrieved April 20, 2010 from http://en.wikipedia.org/wiki/File:Example_of_a_cold_front.svg