Transcript Slide 1

STORMS
A tornado is a violently
rotating column of air
extending from a thunderstorm
to the ground
Change in wind direction
Increase in wind speed
Increasing height
Rising air within a thunderstorm
Tornado damage is
measured by the
Category
Damage
Wind
F0
light
40–72 mph
F1
moderate
73–112 mph
F2
significant
113–157 mph
F3
severe
158–206 mph
F4
devastating
207–260 mph
F5
incredible
261–318 mph
Where do most tornadoes hit in the United States?
In the United States, the area where the tornadoes
hit the most is called Tornado Alley. The
states which are in the tornado alley are:
Danger!
Texas
Nebraska
Colorado
Iowa
Illinois
Indiana
Missouri
Arkansas
Tornadoes!
5
What is a hurricane?
• Violent
cyclonic storm
that develops
in the tropical
region
• Wind speeds
http://earthobservatory.nasa.gov/
are > 74 mph Source:
Newsroom/NewImages/images.php3?img_id=680
Rotation and Pressure
In which direction does a hurricane rotate?
COUNTERCLOCKWISE
Is the barometric pressure inside the
hurricane high or low?
LOW
What conditions must be present
for a hurricane to develop?
Source: http://lwf.ncdc.noaa.
gov/oa/reports/fran/fran.html
1. Warm ocean
temperatures (>80˚ F) up
to 60m deep
2. Little to no wind shear
3. Low pressure system at
least 5˚ North or South of
Equator
4. Rotation caused by winds
What is the major source of
energy fueling a hurricane?
Heat Energy evaporating from the
ocean surface
Source: http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/evap.rxml
Hurricane Anatomy
Source: http://hurricanes.noaa.gov/prepare/structure.htm
By what two factors is hurricane
strength measured?
Wind Speed
Barometric Pressure
What is the Scale Used to
Categorize Hurricanes?
Saffir-Simpson Scale
Category
Max Wind Speed
(mph)
Min. Surface
Pressure (mb)
Storm Surge m
(ft)
1
74-96
> 980
1-1.7 (3-5)
2
97-111
979-965
1.8-2.6 (6-8)
3
112-131
964-945
2.7-3.8 (9-12)
4
132-155
944-920
3.9-5.6 (13-18)
5
> 155
< 920
> 5.7 (>19)
Source: http://kids.earth.nasa.gov/archive/hurricane/saffir-simpson.html
Thunderstorms and Rising Air
• Thunder storms are started when air rises,
cools and starts to loose its moisture.
• T-storms are caused by rising humid air
along either a warm or cold front
• The greater the temperature differences,
the more quickly the storm forms
• T-storms are rather short-lived, usually the
cycle lasts an hour or less
3 parts to a T-storm
1. Formation – rising air expands & cools;
condensation occurs, clouds form
2. Mature – precipitation/bad weather
3. Dissipation – clouds disappear
1. A severe snowstorm with strong winds
and poor visibility
2. Winds must exceed 56km (35 mi) per
hour
3. Temperature must be -7 degrees celsius
or lower
When do Blizzards Occur
• Blizzards occur anytime between late fall and early
spring.
How do Blizzards Form
1. When colder air meets warmer air and
begin to twist.
2. Some type of precipitation must be
present in the clouds.
3. Must be a combination of freezing
temperature and heavy winds.
Where Do Blizzards Occur
Blizzards are most common in the:
1.
2.
3.
4.
Northern Mississippi Basin
Central Part of Canada
Russia
Central Great Plains