THE FORMATION OF TROPICAL CYCLONES

Updated November 2007

Now with NEW CYCLONE section - thanks to Jodi John from British School in Manila

http://www.i-am-bored.com/bored_link.cfm?link_id=18340 - excellent animation cycling up through the Saffir Simpson scale

Tropical Cyclone is the generic name for all storms which occur in the regions just north and south of the ITCZ. There are several regional names: hurricane, cyclone, typhoon etc.

Definition: "an intense, circular, low pressure system with strong cyclonic circulation and vigorous airflow"

There are several conditions necessary for these storms to begin to form:

Requires a huge amount of oceanic thermal energy to drive the convection: sea surface temperatures in excess of 26ºC to a depth of 60m are necessary for the required amount of lapse rate steepening and very deep free convection.
Needs a pre-existing weather disturbance to act as the 'parent' vortex. This is associated with an 'easterly wave' which sets off cyclone 'seedlings'. Only about 10% of these disturbances develop into hurricanes, so conditions need to be right for their development.
Needs the spin of the earth applying the coriolis force to increase the spin: tend to form outside of 5ºN & S of the equator, as the force is almost zero at the equator, and then become organised storms polewards of 10ºN & S.
Requires air to converge at the surface and diverge aloft: high pressure in the upper air, but low pressure at ground (or sea) level

Storms are given a series of designations to identify them on synoptic charts:

TD - Tropical Depression - the first stage of

TC1 - Point 1 on the Saffir-Simpson scale - 5 is the largest hurricane - the different levels are determined by wind speeds.

Convection occurs, fuelled by intense oceanic thermal energy. Develops a warm core in association with high rates of evaporation, and subsequent condensation and release of latent heat.

Cyclones occur in a 'season', which is obviously controlled by climate. The position of the ITCZ is the main influence on the length of the season: as the ITCZ moves to the N of the equator in the N hemisphere summer, and then moves S of the equator.

As storms move over the land, they begin to lose their energy rapidly, as they are fed by thermal energy from the tropical sea. They can still be a particular threat once they make 'landfall', and a lot of the effort of forecasting the storms goes into predicting where and when they will make landfall. They can produce dramatic flooding over the land, but friction and a lack of available water for precipitation means that they will soon run out of energy, and the effects will be dissipated.

STRUCTURE

Cloud structure is the classic cylindrical shape, and clouds extend almost up to the tropopause.

Altocumulus and stratocumulus clouds.

Eye of the storm is a central well of subsidence and adiabatic warming of air drawn into the vortex (from high to low pressure as it is moving from aloft...) Eye is mainly cloud free, and has a diameter in tens of kilometres.

Energy is concentrated within 100km of the centre, and it is here that the winds reach their maximum speed. The strongest winds are within 25km of the eye, but the eye itself is calm. Precipitation is also the heaviest in the region of the eye wall, and can be over 500mm in a 24 hour period.

Hurricane Bebe (1972) deposited 755mm of rain between the 23rd and 24th of October in Fiji.

They are also associated with storm surges (where low pressure causes the sea level to rise, so that the tide is much higher than usual), which can reach 15m. Sea level can rise by 1cm for each 1mb drop in pressure.

Hurricanes move slowly: 5-7m a second. Systems are steered from east to west by the trade winds. The track tends to curve polewards over time, due to the spin of the earth.

Once the remains of the depression reaches mid-latitude, it can be incorporated into a mid-latitude depression.

One of the most devastating hurricanes in recent years was Hurricane Mitch, which hit Honduras particularly badly.

TYPHOON !!!

A personal account of Typhoon Milenyo / Xangsane (September 2006)

Here is a brief summary of the background:

"I have lots of information on typhoon Milenyo (international name Xangsane) a super typhoon which hit the Philippines in September 2006 (tracking exercises, DME, PPT, eye witness account etc).
About 180 people died, but the numbers are not accurate.

Interesting effects which are never touched upon in text books include:

Dengue fever reduced for 2 months afterwards due to mosquito breeding grounds being destroyed. It's now even worse though.
Government order to take down high rise commercial signs after they fell and killed people. On one road alone (called EDSA kind of similar to the north circular in London) 3586 were taken down in less than a month and there's still thousands along there!

Weather has gone crazy out here, had two more super typhoons in December, the season is normally over by September. The last super killed over 1000 people so despite politicians' noises still more needs to be done.

An effect of the earthquake over the Christmas holidays in Taiwan is my broadband is still down...."

RESOURCES (links to be added soon)

A Personal Account of the Typhoon by Jodi John (Word document)

Pictures of Cyclone - large file - hosted at 4Share - e-mail for details

DME (Powerpoint file) and DME WORD (Word document)

Typhoon Tracking Chart (GIF)

5Ws Starter (Word Document) - apparently the umbrellas in the picture were all recycled...)

Typhoon Instructions (Word document)

Thanks to Rob Chambers for a recent posting on SLN which provided a long list of useful links - check these out ! (Also covers TORNADOES...)

• Hurricane and Tropical Cyclone Formation http://www.aerospaceweb.org/question/atmosphere/q0242.shtml
• Hurricane Visualisations http://serc.carleton.edu/NAGTWorkshops/visualization/collections/hurricanes.html
• Hurricane Formation Diagram http://www.windows.ucar.edu/tour/link=/earth/images/hurricane_formation_jpg_ima ge.html&edu=elem
• Hurricanes Animated – BBC Guide http://news.bbc.co.uk/1/hi/sci/tech/4588149.stm can be downloaded here http://www.bbc.co.uk/apps/ifl/schools/archive/showrecord?Id=33
• Hurricane Viewer – part of the new NASA Hurricane Portal – see animations of Hurricane Pathways http://disc.gsfc.nasa.gov/hurricane/HurricaneViewer.shtml
• Hurricane Portal – new website just launched by NASA http://disc.gsfc.nasa.gov/hurricane/index.shtml
• Pictures and article related to Hurricane Keith http://sanpedrosun.net/old/00-371.html
• Hurricane Tracker - Check out this one – how good will this look on the data projector!http://images.ibsys.com/sh/hurricanetracker/hurtracker.swf
• Tornado Video Footage (great for use with the data projector / interactive whiteboard) http://www.stormvideo.com/tornado/index.html
• Cyclone Tours Promo Video http://www.cyclone-tours.com/promo_video.htm
• An interactive guide to Hurricane Science and Safety for students http://meted.ucar.edu/hurrican/strike/
• Twister – how does the Hollywood film distort real life? http://www.cimms.ou.edu/~stumpf/twistint.html
• More violent storms and Tornadoes hit the US (April 2006) http://news.bbc.co.uk/1/hi/world/americas/4890342.stm
• El Niño may be morphing to La Nina http://earthobservatory.nasa.gov/Newsroom/NewImages/images_topic.php3?img_id=17 581&topic=oceans
• Tornado Guide – an excellent tornado guide from NOAA, Fema etc. http://www.nssl.noaa.gov/edu/safety/tornadoguide.html

Hurricane Katrina (August 2005):
• What it was like in and around the Superbowl – some very useful information / photographs here http://sports.espn.go.com/espn/eticket/story?page=superdome&lpos=spotlight&lid=tab1pos1
• How things have changed one year on – an interactive guide from the Guardian website http://www.guardian.co.uk/katrina/0,,1560620,00.html - includes a flash comparison of a series of photographs between the time of the flooding and now http://www.guardian.co.uk/flash/0,,1860465,00.html
• A flash animation of New Orleans being flooded during Hurricane Katrina (you may need to click outside the US to view) http://www.nola.com/katrina/graphics/flashflood.swf
• Teaching about Hurricane Katrina http://artofteachingscience.org/katrina/katrina.html
• Hurricane Katrina Animation – a fantastic animation of Hurricane Katrina in Google Earth (requires Google Earth 4 to run) http://www.gearthblog.com/blog/archives/2006/09/katrina_time_animati.html
• Hurricane Katrina – In Pictures: Katrina’s Trailer Park Refugees http://news.bbc.co.uk/1/shared/spl/hi/picture_gallery/06/in_pic tures_katrina0s_trailer_park_refugees/html/1.stm
• Surviving Hurricane Katrina http://www.margaretmedia.com/katrina/survivingkatrina.pdf (A diary of the disaster)
• Effect of Hurricane Katrina on New Orleans http://en.wikipedia.org/wiki/Effect_of_Hurricane_Katrina_on_New_Orleans

BIRMINGHAM TORNADO – JULY 2005
• Tornado injures 19 in Birmingham http://news.bbc.co.uk/1/hi/england/west_midlands/4725279.stm
• In Pictures – Birmingham Tornado http://news.bbc.co.uk/1/hi/in_pictures/4725711.stm
• Birmingham Tornado – Wikipedia http://en.wikipedia.org/wiki/Birmingham_Tornado_(UK)
• Birmingham’s Hard Tornado lesson http://news.bbc.co.uk/1/hi/england/west_midlands/6161199.stm
• Tornado Hits Birmingham http://www.bbc.co.uk/birmingham/content/articles/2005/07/28/tornado_feature.shtml
• Photos of the tornado in Birmingham http://www.birmingham.gov.uk/GenerateContent?CONTENT_ITEM_ID=64253&CONTENT _ITEM_TYPE=0&MENU_ID=11616
• Birmingham Tornado – Emergency Response http://www.birmingham.gov.uk/GenerateContent?CONTENT_ITEM_ID=64484&CONTENT_I TEM_TYPE=0&MENU_ID=198

LONDON TORNADO LINKS (December 2006):
• 6 hurt as tornado hits London http://news.bbc.co.uk/1/hi/england/london/6217514.stm
• Tornado Families being rehoused http://news.bbc.co.uk/1/hi/england/london/6162225.stm
• Battered Homes to be demolished http://news.bbc.co.uk/1/hi/england/london/6220000.stm
• After the Dust has settled http://news.bbc.co.uk/1/hi/england/london/6161453.stm
• In Pictures: Trail of Destruction http://news.bbc.co.uk/1/hi/in_pictures/6217898.stm
• Claiming for the Tornado Damage http://news.bbc.co.uk/1/hi/business/6220380.stm
• Animated Guide - Tornadoes http://news.bbc.co.uk/1/hi/world/5328524.stm
• Tornado Victim’s Future uncertain http://news.bbc.co.uk/1/hi/england/london/6220420.stm

And here's another list that Rob did in August 2007

1. Hurricane Dean
2. The earthquake in Peru
3. Floods in South Asia

Thought they might be useful if planning uptodate bits ready for school

Video links:
• Hurricane Dean strikes Mexico http://www.bbc.co.uk/mediaselector/check/player/nol/newsid_6950000/newsid_6956100?redirect=6956151.stm&news=1&nbram=1&bbwm=1&bbram=1&nbwm=1&asb=1
• Prediction for Dean’s Path http://www.bbc.co.uk/mediaselector/check/player/nol/newsid_6950000/newsid_6956400?redirect=6956461.stm&news=1&nbram=1&bbram=1&nbwm=1&bbwm=1&asb=1

Hurricane Information
• Hurricane Dean – including tracking information http://www.moreweather.com/tropics/moreweather.php3#DEAN
• Map of Hurricane Dean’s Path http://www.nhc.noaa.gov/refresh/graphics_at4+shtml/024526.shtml?hwind120#contents
• Interactive Guide – Hurricanes Explained (The Guardian) http://www.guardian.co.uk/flash/0,,773980,00.html
• Hurricane Dean – are you affected? Have your say http://newsforums.bbc.co.uk/nol/thread.jspa?threadID=7144&&edition=1&ttl=20070821145150
• Hurricane Dean hits the Caribbean http://www.bbc.co.uk/weather/world/news/17082007news.shtml

Hurricane Dean - Pictures:
• In Pictures – In Dean’s Path (The Guardian) http://www.guardian.co.uk/environment/gallery/2007/aug/20/1?picture=330600770
• In Pictures: Hurricane Dean (20/8/07) http://news.bbc.co.uk/1/hi/in_pictures/6952788.stm
• In Pictures: Dean rushes for Mexico 21/08/07 http://news.bbc.co.uk/1/hi/in_pictures/6956117.stm
• In Pictures: Hurricane Dean 20/08/07 http://news.bbc.co.uk/1/hi/in_pictures/6955296.stm
• In pictures - Hurricane blasts Caribbean (20/08/07) http://news.bbc.co.uk/cbbcnews/hi/newsid_6950000/newsid_6953900/6953956.stm

Chronological News Reports – PERU EARTHQUAKE – AUGUST 2007

• Powerful Earthquake Rocks Peru (16/08/07) (Newsround) http://news.bbc.co.uk/cbbcnews/hi/newsid_6940000/newsid_6948900/6948983.stm
• Scores Killed in Peru Earthquake (16/08/07) http://news.bbc.co.uk/1/hi/world/americas/6948888.stm
• Hundreds Dead in Powerful Peru Earthquake (16/08/07) http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/08/16/wquake316.xml
• Peru Earthquake Kills 500 (16/08/07) http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2007/08/16/wquake416.xml
• 450 killed in Peru Quake (16/08/07) http://www.guardian.co.uk/naturaldisasters/story/0,,2149760,00.html
• Background: Peru Earthquakes (16/08/07) http://www.guardian.co.uk/naturaldisasters/story/0,,2150290,00.html
• “The Earth was like Jelly” – hundreds die in Peru quake, but Lima escapes (The Guardian) (17/08/07) http://www.guardian.co.uk/naturaldisasters/story/0,,2150628,00.html
• Peru coast hit by powerful aftershock (17/08/07) http://www.guardian.co.uk/naturaldisasters/story/0,,2150891,00.html
• Fresh earthquake strikes Peru (17/08/07) – Newsround
• http://news.bbc.co.uk/cbbcnews/hi/newsid_6950000/newsid_6950700/6950770.stm
• Peru rattled by fresh earthquake (17/08/07)
• http://news.bbc.co.uk/1/hi/world/americas/6951836.stm
• Dawn shines light on Pisco’s sorrow (17/08/07) http://news.bbc.co.uk/1/hi/world/americas/6951443.stm
• Peru Quake – Eyewitness Accounts (17/08/07)
• http://news.bbc.co.uk/1/hi/talking_point/6949537.stm
• Peru sends soldiers to quell quake looting (The Guardian) (19/08/07) http://www.guardian.co.uk/naturaldisasters/story/0,,2151928,00.html
• Hopes fade for Peru quake victims (20/08/07) http://news.bbc.co.uk/1/hi/world/americas/6955295.stm

Map of Earthquake Area - Where the earthquake happened (Good graphic from the Guardian) http://www.guardian.co.uk/graphic/0,,2149958,00.html

Pictures - Peru Earthquake:

• In Pictures: Lima Earthquake (The Guardian) http://www.guardian.co.uk/news/gallery/2007/aug/16/internationalnews?picture=330581318
• In Pictures – Peru Earthquake (16/08/07)
• http://news.bbc.co.uk/1/hi/in_pictures/6949478.stm

Chronological News Reports – SOUTH ASIA FLOODS – AUGUST 2007

• Millions hit by South Asia Floods (03/08/07) http://news.bbc.co.uk/1/hi/world/south_asia/6922484.stm
• South Asia considers flood lessons (03/08/07) http://news.bbc.co.uk/1/hi/world/south_asia/6929734.stm
• Devastating Floods hit South Asia (03/08/07)
• http://news.bbc.co.uk/1/hi/world/south_asia/6927389.stm
• Monsoon Floods displace 19 million (Guardian) (03/08/07) http://www.guardian.co.uk/india/story/0,,2141060,00.html
• Desperate bid to save Asian Flood Victims (05/08/07) http://www.guardian.co.uk/india/story/0,,2141938,00.html
• Fears of epidemics follow lethal floods in Southern Asia (06/08/07) http://www.guardian.co.uk/india/story/0,,2142266,00.html
• Agencies struggling to get Aid to flood victims (7/08/07) http://www.guardian.co.uk/naturaldisasters/story/0,,2143280,00.html
• South Asia Flood Toll Rises (7/08/07) http://news.bbc.co.uk/1/hi/world/south_asia/6932636.stm
• Aid struggles to reach marooned millions after South Asia Floods (8/08/07) http://www.guardian.co.uk/naturaldisasters/story/0,,2143744,00.html
• UK plea for South Asia Flood Cash (08/08/07) http://news.bbc.co.uk/1/hi/uk/6936154.stm
• South Asia Victims face health crisis (08/08/07) http://news.bbc.co.uk/1/hi/world/south_asia/6935847.stm
• South Asia Floods – Worst hit Areas (09.08/07) http://news.bbc.co.uk/1/hi/world/south_asia/6929004.stm
• Surviving on snails and rats in Bihar (09/08/07) http://news.bbc.co.uk/1/hi/world/south_asia/6937267.stm
• Flood Rains hit New India Regions (09/08/07) http://news.bbc.co.uk/1/hi/world/south_asia/6938350.stm
• Infections spread as toll from Asian monsoon reaches 2000 (11/08/07) http://www.guardian.co.uk/naturaldisasters/story/0,,2146672,00.html

Floods in South Asia Pictures
• In Pictures: Floods in South Asia (03/08/07) http://news.bbc.co.uk/1/hi/in_pictures/6927778.stm
• In Pictures: Bangladesh Floods (06/08/07) http://news.bbc.co.uk/1/hi/in_pictures/6933033.stm
• In Pictures: South Asia Flood Relief (07/08/07)
• http://news.bbc.co.uk/1/hi/in_pictures/6935745.stm
• Flooding in Asia (Guardian Gallery) http://travel.guardian.co.uk/Guardian/environment/gallery/2007/aug/03/flooding.internationalnews

General Info about Monsoon
• The Asian Monsoon (BBC Weather) http://www.bbc.co.uk/weather/features/understanding/monsoon.shtml
• What is the South Asian Monsoon http://news.bbc.co.uk/1/hi/world/south_asia/6929988.stm

Cheers for these.

CYCLONE SIDR

BANGLADESH - Cyclone Sidr Resources

Tony Cassidy spent the October half term of this year in Bangladesh.
As part of his travels, he was asked to create a resource.
The week after he arrived back in England, CYCLONE SIDR hit Bangladesh: the worst cyclone since 1991.

Details of the CYCLONE can be seen on the BBC NEWS site, and there is a very detailed article from the DAILY TELEGRAPH here.

The resource that Tony created is designed to be suitable for Key Stage 3 pupils.

Lesson Ideas Resources

1 Rationale- why study this event?Formation of the Cyclone Sidr.
Cyclone protection in Bangladesh.
PowerPoint with linked video and embedded animation.Student worksheet about the formation of the cyclone.

2 Causes, Impacts & Responses. PowerPoint introducing classification task.Student worksheet-classification task.

3 How quickly will Bangladesh cover? PowerPoint comparing development statistics of the U.K. and Bangladesh.Student response worksheet.

4,5,6 Levelled assessment. Students to produce a PowerPoint storyboard about the cyclone for B.B.C. news 24.Task worksheet.
Assessment criteria.

Outline PowerPoint.

The resources are a hefty 26Mb download.

If you use the resources, please make a donation to the OXFAM DISASTER RELIEF FUND. Click the link below, or the logo at the top of this post.

OXFAM DISASTER RELIEF FUND

RETURN TO 'A2' METEOROLOGY PAGE

Lesson	Ideas	Resources
1	Rationale- why study this event?Formation of the Cyclone Sidr. Cyclone protection in Bangladesh.	PowerPoint with linked video and embedded animation.Student worksheet about the formation of the cyclone.
2	Causes, Impacts & Responses.	PowerPoint introducing classification task.Student worksheet-classification task.
3	How quickly will Bangladesh cover?	PowerPoint comparing development statistics of the U.K. and Bangladesh.Student response worksheet.
4,5,6	Levelled assessment.	Students to produce a PowerPoint storyboard about the cyclone for B.B.C. news 24.Task worksheet. Assessment criteria. Outline PowerPoint.