activity 2 powerpoint
DESCRIPTION
Activity 2 Powerpoint: Hurricane formation and characteristicsTRANSCRIPT
This work is supported by a National Science Foundation (NSF) collaboration between the Directorates for Education and Human Resources (EHR) and Geociences (GEO) under grant DUE - 1125331
Hurricane Formation:Ocean and Atmosphere Systems
Interact to Create Hurricanes
Questions
• What is a hurricane?• What four conditions are necessary for hurricane formation?• What happens as hurricanes approach land?
What is a Hurricane?
• Make a list of hurricane characteristics:
What is a Hurricane?
• Formal definition:An intense low pressure system with sustained winds >74 mph
What Makes a Hurricane?
• Four essential ingredients
What Makes a Hurricane?1) Warm SST >26.5°C (80°F) over large area
What Makes a Hurricane?
1) Warm SST (>26.5 C) over large area2) Instability in atmosphere (rising air mass, beneath which surface
winds converge)
What Makes a Hurricane?
1) Warm SST (>26.5 C) over large area2) Instability in atmosphere (rising air mass)3) Little/no vertical wind shear through atmosphere to tropopause
(ocean)
(atmosphere)
(tropopause)
Which wind profile has too much vertical shear for hurricanes to form?
What Makes a Hurricane?
1) Warm SST (>26.5 C) over large area
2) Instability in atmosphere (rising air mass)
3) Little/no vertical wind shear through troposphere
4) Sufficient latitude >5-10o off equator
Hurricanes are powered by:
• latent heat stored in water vapor– released when water condenses
1. Warm water supplies sensible heat and humidity to overlying air
2. Air decreases density; rises
3. Air cools; H2Ovapor condenses
4. Latent heat released-- Heat warms air; rises faster
5. P gradient increases -- Faster winds converge at the low pressure center
-- More water vapor into system!
Feedback between the ocean and atmosphere systems!
Can Hurricanes Cross the Equator?
• Discuss with the person next to you. • Why or why not?
Can Hurricanes Cross the Equator?
– Discuss with the person next to you. – Why or why not?
(Hurricane tracks 1985-2005; NASA)
North Atlantic Hurricane Season is June-November
Most storms occur in which month?
January
Febru
ary
Marc
hApril
May
June
July
August
September
October
November
December
0
0.5
1
1.5
2
2.5
3
3.5
4
Tropical StormsHurricanesHurricanes w/US Landfall
Ave
rage
num
ber p
er m
onth
, 185
1-20
11
Which of these things would cause a hurricane to lose energy?
a) Moving over colder waterb) Moving over warmer waterc) Making landfalld) Crossing the ocean
As a hurricane approaches land
Wind and Rain
(NOAA)
Storm Surge
(NASA)
As hurricanes make landfall, they decrease in strength
Why?
Remember what fuels hurricanes…
Warm water!
Draw:
• The relationships between the ocean, atmosphere, and people in a hurricane.
Make sure you can now answer these:What is a hurricane?
- What four conditions are necessary for hurricane formation?
- What happens as hurricanes approach land?
References• Slides 4 and 5. Public Domain Image of Hurricane Rita as a Category 5 hurricane. http
://www.nnvl.noaa.gov/hurseas2005/Rita2045zD-050921-1kg12.jpg• Slide 6. Public Domain Image of SST. http
://www.osdpd.noaa.gov/data/sst/fields/FS_km10000.gif• Slide 7. Public Domain illustration of tropical waves. http://www.aoml.noaa.gov/hrd/tcfaq/
Twaves.jpg• Slide 9. Creative Commons illustration of hurricane forces: http://en.wikipedia.org/wiki/
File:Hurricane_isabel_and_coriolis_force.jpg• Slide 12. Public Domain image of hurricane tracks: http://www.nasa.gov/images/content/
313775main_global_hurr_tracks_HI.jpg• Slide 15. Public Domain image of Hurricane Eloise approaching shore.http
://www.photolib.noaa.gov/historic/nws/images/big/wea00416.jpg• Slide 17. Public Domain illustration of storm surge.http
://earthobservatory.nasa.gov/Library/Hurricanes/Images/storm_surge.gif• Slide 18. Public Domain image of 2012 hurricane tracks. http://www.nhc.noaa.gov/
2012atlan.shtml• All other illustrations and text were created by Lisa Gilbert under a Creative Commons Attribution-NonCommercial-
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