1. 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.
2. TABLE OF CONTENTS
Fronts
Activity: Predicting the Weather
Quiz: Fronts
Severe Weather
Simulation: How Cumulus Clouds Form
Quiz: Severe Weather
3. 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.”
4. 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.
5. 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.
6. SLOW MOVING COLD
FRONT
Lifts warm air more slowly
Produces weaker storms
Produces lighter precipitation
7. 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
8. 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
10. 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
13. PRACTICE PREDICTING
THE WEATHER
Predict the Weather
Directions:
1.) Click on the picture above
2.) 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 score
5.) Repeat for Levels 2 & 3
14. QUIZ: FRONTS
CLICK 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.
17. QUIZ: FRONTS
CLICK 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
20. QUIZ: FRONTS
CLICK 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.
23. QUIZ: FRONTS
CLICK 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.
26. 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
27. 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
29. 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
31. 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
32. 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
34. 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
35. 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
38. 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.
41. 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.
44. 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
47. 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.
50. 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
51. 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
