1. Cyclones:
Tropical and Midlatitude cyclones
PRESENTATION BY: BRYAN B. SHINGANGE

2. TYPES OF CYCLONES
 TROPICAL CYCLONES
 MID-LATITUDE CYCLONES
 MESOCYCLONES
 POLAR CYCLONES
• Out of all the aforementioned types of cyclones, our focus in this
presentation is on the Tropical Cyclones and Midlatitude Cyclones

4. Cyclone

5. Where do tropical cyclones occur?

6. Location and Typical paths of tropical Cyclones
• If the storm occurs in the Atlantic Ocean and North-
east Pacific, it's called a hurricane
• If the exact same type of storm occurs in the North-
west Pacific, this is a typhoon
• And if we find those same storms in the South
Pacific and Indian Ocean, these are called tropical
cyclones.
• Tropical cyclones develop within 5 and 30 degrees
of latitude.
 Because they require ocean waters of 80 degrees
Fahrenheit or so to form cyclone. ( primary condition
for the formation of tropical cyclone) How dose it
occur?
This Photo by Unknown Author is licensed under CC BY

7. How do they occur
• for a cyclone to form, warm, moist air over the ocean rises upward
• As this air moves up and away from the ocean surface, it leaves is less air
near the surface.
• So basically, as the warm air rises, it causes an area of lower air pressure
below.
• Air from surrounding areas with higher air pressure pushes into the low
pressure area.
• Then this new "cool" air becomes warm and moist and rises, too. And the
cycle continues...

8. Cont…
• As the warmed, moist air rises and cools the water in the air forms clouds
• As the cycle continues, more air rises up and cloud becomes thick
• Condensation then releases the latent heat of energy stored in the water vapour (
power for cyclone)
• The whole system of clouds and wind spins and grows, fed by the ocean's heat and
water evaporating from the ocean surface
• The system spins due to the Coriolis effect
• The Coriolis effect makes storms swirl clockwise in the Southern hemisphere and
counter-clockwise in the Northern Hemisphere.

9. Cont…
As the storm system rotates faster
and faster, an eye forms in the
centre.
— It is very calm and clear, with
very low air pressure. Higher
pressure air from above flows down
into the eye.
When the winds in the rotating
storm reach 39 mph (63 kmph), the
storm is called a "tropical storm".
And when the wind speeds reach
74 mph (119 kmph), the storm is
officially a "tropical cyclone' or
hurricane.
Tropical cyclones usually weaken
when they hit land, because they
are no longer being "fed" by the
energy from the warm ocean
waters.
However, they often move far
inland, dumping many centimeters
of rain and causing lots of wind
damage before they die out
completely
This Photo by Unknown Author is licensed under CC BY-SA
This Photo by Unknown Author is licensed under CC BY-NC

10. STAGES OF DEVELOPMENT
1
Formative stage
2
Immature stage
3
Mature Stage
4
Degeneration stage

11.  Formative stage
Pressure is still
above 1000 hPa
High sea/air
temperature
Cirrus, cumulus
cloud and light rain
Winds reach gale
force—(60km/h)
Small area is
influenced (about 20
km from the eye)

12.  Immature stage
Air pressure in the eye (centre of the cyclone) fall below 1000 hPa and still decreasing
The vortex contract and the storm intensify as more evaporation and condensation occur
Cumulonimbus clouds surround the eye to a height of 12 km up because the vortex is pushing the clouds
Hurricane wind speed (120km/h) within 50 km from the eye and gale force winds within 500 km from the eye.
In this stage, a large area is influenced. About 600 km in diameter

13.  Mature Stage
Air pressure of about 900-940
hPa
Warm moist air still converges,
unstable air rises around the
centre, air sinks into the centre
at the upper level of the system
Heavy rain from cumulonimbus,
160km from the eye
Hurricane winds (177) extended
to 300km from the eye
Worse weather in the active
quadrant
This stage can last up to seven
days
This Photo by Unknown Author is licensed under CC BY-SA
The structure of a matured TC

14.  Degenerating/Dissipation Stage
• At this stage, the tropical cyclone reaches the land
• Pressure in the eye rises when the land is reached
• Temperature decreases
• Less moisture is fed into the system
• The wind speed decreases
• The area affected shrinks (get reduced drastically)
• This is the stage where tropical cyclones die when they reach land (this is
due to friction force posed by trees, building and mountains altogether
with the rough Earth’s surface.

15. Strategies to help prepare for a tropical cyclone
• avoid crossing flooded rivers
• farmers should move pumps away from rivers
• people staying close to rivers should evacuate
• small to medium sized boats should remain at ports for few days after a
tropical cyclone

16. Midlatitude cyclones

17. Midlatitude Cyclones
• These systems are also known as temperate/extratropical cyclones
• The cyclonic storms that develop in the middle latitudes. (Between 30° and
60° latitude from the equator)
• These cyclones develop where sharp temperature gradients exist between
adjoining air masses.
• extratropical cyclones produce rapid changes in temperature and dew point
along broad lines, called weather fronts, about the center of the cyclone.
• Extra tropical cyclones form as waves along weather fronts before
occluding later in their cycle as cold core cyclones

18. Cont…
• The winds are generally weaker.
• Formed by:
Cyclogenesis:
 development of cyclonic circulation in atmosphere.
Extra tropical transition:
 process by which a tropical cyclone upon encountering with a baroclinic
environment and reduced sea surface transforms into an extra tropical
cyclone

19. Where do mid-latitude cyclones form
• Midlatitude cyclones occur between 30◦ and 60◦
north and south of the equator.
• They occur mainly over oceans and coastal areas.
• These cyclones affect regions between 35◦s and
70◦s in the South Africa. The southern tip is 37◦,
so the cold front only crosses the southern cape.
• Cold fronts only reach the interior of South Africa
in winter, because during this season all the
pressure belts move slightly north. • Hence, this is
the reason Western cape province have very cold
winters.
NB: These systems are common in South Africa as
they very often affect the western cape province

20. Stages of development (Midlatitude cyclones)

21. Effects of Midlatitude cyclones in western cape, South africa
The southwestern tip of the country has a Mediterranean
climate, with hot dry summers and cool wet winters. This is
because mid-latitude cyclones migrate further north during
winter, allowing the edge of the cold front arm to sweep
across the southern
midlatitude cyclones result causef the country.
-extreme rainfall leads to flooding
-gale force winds result in sea surges, destruct powerlines
-cold front bringing very cold conditions as it arrives
-when warm front arrive, the temperatures rises sharply and
can affect those with high blood pressure negatively
-cause rainfall in during winter seasons
-Provide water for irrigation
-minimize the effects of berg by cooling down temperatures

23. Bibliography
Sony, E. (2019). Cyclone. Available from Slideshare at:
https://www.slideshare.net/ElsaSony/cyclone-159314192 (Accessed 17 August 2022)
Manhas, A. (2017). Cyclones. Available from Slideshare at:
https://www.slideshare.net/AmitManhas3/cyclones-71360806 (Accessed 17 August 2022)
Smith, S. (2010). Cyclone Power Point. Available from Slideshare at
https://www.slideshare.net/StaceySmith/cyclone-power-point (Accessed 17 August 2022)
Mahmood, J. (2012). Cyclones. Available from Slideshare at:
https://www.slideshare.net/mahmoodjan71/cyclones-15006332 (Accessed 17 August 2022)
Mashakgomo, C. (2014). Tropical Cyclones. Available from Slideshare at:
https://www.slideshare.net/caswell7/tropicalcyclones-111130083054phpapp01?qid=a2f17957-
3be3-4d50-9689-41e4161e05aa&v=&b=&from_search=3 (Accessed 17 August 2022)