Download presentation
Presentation is loading. Please wait.
Published byAshlie Stewart Modified over 6 years ago
1
Bell Ringer Cumulonimbus clouds have a tall structure and a flat base. What are they usually associated with?
2
Thunderstorms and Tornadoes
Severe Storms Thunderstorms and Tornadoes
3
What do you know about Thunderstorms?
4
Have you ever seen a small whirlwind carry dust or leaves upward on a hot day?
5
Thunderstorms A storm that generates lightning and thunder.
Frequently produce gusty winds, heavy rain, and hail. Associated with cumulonimbus clouds
6
Lightning: results from the build up and discharge of electric energy between positively (ground) and negatively (clouds) charged area Thunder: the sound of rapidly expanding gases usually associated with lightning
7
Warm Up What causes lightning? What causes thunder? True or False: Lighting can strike 10 miles away from the storm cloud. What causes clouds to form? What type of pressure is found in the center of a storm?
8
Warm Up What causes lightning?
A build up of negative charges in the clouds discharges to the positively charged surface What causes thunder? When lightning strikes, it super heats the air and the instant heating causes the air to expand suddenly. True or False: Lighting can strike 10 miles away from the storm cloud. True What causes clouds to form? Rising air pulls water moisture into the atmosphere. As the moisture cool, it condenses into clouds What type of pressure is found in the center of a storm? Low
9
How common are thunderstorms?
10
Occurrence of Thunderstorms
Estimated 2000 in progress on Earth at any time About 45,000 take place each day More than 16 million occur annually around the world
13
The greatest number occur in the tropics
Atmospheric Conditions needed: Warm, moist air, uplift, and instability
14
Development of Thunderstorms
Form when warm, humid air rises in an unstable environment 3 Stages Cumulus Stage Mature Stage Dissipating Stage
15
Cumulus Stage Warm, moist air is supplied to the cloud by strong updrafts Cloud grows vertically
16
Mature Stage Begins within 1 hour of the initial updraft
Most active stage Heavy precipitation, gusty winds, lightning, and sometimes hail are produced
17
Dissipating Stage Cloud begins to evaporate
The cooling effect of the falling precipitation and the flowing in of colder air from high above causes the storm to die down
18
Thunderstorm Development
The Thunderstorm Recipe Video
19
What do you know about tornadoes?
20
Tornadoes Violent low pressure windstorms that take the form of a vortex. Vortex- spinning/rotating, often turbulent, column of air The vortex extends downward from a cumulonimbus cloud – produce rain and hail Move counterclockwise
21
Occurrence of Tornadoes
About 770 tornadoes are reported in the United States each year Frequency is greatest between April and June Associated with Severe Thunderstorms
22
Which states in the U. S. do you think get the most tornado touchdowns?
23
Development of Tornadoes
Most form in association with severe thunderstorms The formation of the mesocyclone is an important process in tornado formation. National Geographic Tornadoes Video
24
Mesocyclone A vertical cylinder of rotating air that develops in the updraft of a thunderstorm
25
Formation of a Mesocyclone
How Tornadoes Form Video
26
Tornado Intensity Pressure within tornadoes can be as much as 10% lower than the pressure outside the storm. Intensity is measured on the Fujita Scale
27
Fujita Scale First introduced in 1971 – Tetsuya Fujita
Measures the strength of tornadoes Based on storm damage Ranges from F0-F5 Updated 2007 – Enhanced Fujita Updated wind speeds match damaged caused by tornado
28
Fujita Tornado Intensity Scale
Enhanced Fujita Scale
29
Fujita Tornado Scale Category Winds (MPH) Winds (KPH) Damage F0 <73
<116 Light damage F1 73-112 Moderate Damage F2 Considerable Damage F3 Severe Damage F4 Devastating Damage F5 >260 >419 Incredible and Speechless Damage
30
Watch vs. Warning
31
Tornado Watch Alert people to the possibility of tornadoes in a specified area for a particular time Conditions are right for a tornado to happen
32
Tornado Warning Issued when a tornado has actually been sighted in an area or; Indicated by weather radar
33
Exit Ticket Severe Storms Causes Effects Thunderstorms a) b) Tornadoes
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.