1. Hurricanes
An Ocean-Atmosphere Hazard

2. Syllabus Link
The formation,
distribution and
physical impacts of
hurricanes on coastal
margins, including
storm surges

3. Definition
A tropical cyclone is a
rapidly rotating storm
system characterized by
a low pressure center, a
closed low-level
atmospheric
circulation, strong winds,
and a spiral arrangement
of thunderstorms that
produce heavy rain.

4. Same same but different
Depending on its location and strength, a
tropical cyclone is referred to by different
names, including hurricane, typhoon, tropical
storm, cyclonic storm, tropical depression, and
simply cyclone.

5. Same same but different
In what location are tropical cyclones referred to
in these terms?
1. Hurricane
2. Typhoon
3. Tropical cyclone
4. Willy willy

6. Same same but different
In what location are tropical cyclones referred to
in these terms?
1. Hurricane – Atlantic & N.E. Pacific
2. Typhoon – Asia
3. Tropical cyclone – South Pacific, Indian ocean
4. Willy willy - Australia

7. Hurricane Formation

8. Hurricanes: Formation

9. Recipe for a Hurricane
• First you need warm waters (at the equator, needs to be
over 26 degrees C). Warm water = warm air.
• The warm air rises, and condenses into clouds
• Then this forms a low pressure system in the vertical
column and the ‘rising warm air’ begins to circle around
this. Air pressure drops because of this and new air
flows to this low pressure
• The winds circling gain speed which …. Dum dum dum…

10. Hurricanes: Formation

11. Hurricanes: Formation
• As these winds at the equator collide
near the surface of the water they push
each other up in the column.
• They rise and condense in clouds and
create a low pressure system in the
center… which then starts ‘sucking’ up
the water in the center like a vortex
• As warm air and moisture rises, more
must fill its place. Repeating the process-
once it starts it is hard to stop.
• But the hurricane constantly requires
warm air to power it.
• Cooler dense air collects at top and the
warm air rises up and ‘billows’ up above.
• These clouds bring the rain and thunder
storms.

12. Hurricanes: Formation
As the
‘winds’ gain
strength (ie
speed) the
term changes
from tropical
depression,
to storm, to
hurricane

13. Hurricanes- How are they measured?

14. Hurricanes- How are they measured?

15. Hurricane Distribution:
Where do they occur?

16. World Wide Terminology…

17. Where do they occur most frquently?

18. When do they occur?
Reliant on the
warm season
temperatures
near the
equator of
water and wind.

19. Hurricanes: Connections
• What is the relationship between atmosphere
and ocean in the ‘formation’ of a hurricane?
• How does El Nino and La Nina effect hurricanes?
• How does the Corolis effect connected to
hurricanes?
• How are hurricanes connected to global
warming?

20. Hurricane Impacts

21. Hurricane- Impacts
Many assume the Hurricane itself is the most
destructive- the wind, and rain
–The wind and rain brings with is
precipitation, flooding and landslides, hail
–The wind brings waves and flooding
–The wind itself can be destructive enough
to blow the roof off a house!
• But in fact it is also the ‘storm surge’ that is
argued to be worse

22. Hurricane- Impacts
High Winds--This is an
important effect of a
hurricane since it
determines how powerful
the storm is, and how
much storm surge and
damage it can cause.
Winds in a hurricane can
reach over 300 kph.

23. Hurricane- Impacts
Heavy rain and flooding--This is the effect of a
hurricane that is completely taken for granted.
After hurricanes make landfall, and their winds
abate, the tremendous amounts of rainfall
become a major factor, and can cause significant
flooding as with hurricane Harvey in
Houston last year.

24. Hurricane- Impacts
Storm surge and tidal flooding--This is the most
devastating and notable effect from a hurricane.
Storm surge is the rising wall of water the comes
ashore with a hurricane, and is responsible for
90 percent of all hurricane related deaths.