A short presentation to demonstrate the role of the ITCZ in drought and hurricane formation for IB geography students

1. Understanding Global Climate
The Inter Tropical Convergence Zone
and its Relevance to Droughts and
Hurricanes

2. What Goes Up…………………………….The
Inter Tropical Convergence Zone and its
Relevance to Hurricanes

3. The ICTZ is the band of cloud that you can see here; it wraps the whole way around
the Earth underneath the solar equator

4. The ITCZ and Hurricanes
The reason why there are clouds at the ITCZ is that there is a lot of evapotranspiration occurring.
This evapotranspiration is due to the sun being directly overhead. This evapotranspiration is the
first stage of hurricane formation; the development of low pressure areas.
Low
pressure
at surface

5. Summer in the Northern Hemisphere is when the sun is directly Summer in
over the Tropic of Cancer the Southern
Hemisphere is
when the sun
is directly
over the
Tropic of
Capricorn

6. The movement of the ITCZ as the seasons change has a huge influence over global climate as
the weather associated with the ITCZ migrates with it.

7. You should be able to see that oceans north of the Equator are currently hotter than those
south of the Equator: This is because the sun is over the northern hemisphere at the moment.
You should also notice that the significant tropical storms and low pressure systems are all in the
northern hemisphere at the moment
Equator

8. The movement of the solar equator (and thus the ITCZ) is crucial for the formation of hurricanes
for these 2 reasons:
1. It creates low pressure areas 2. It warms the ocean which provides the
of convection rainfall that are hot water fuel that allows low pressure
embryonic hurricanes areas to mature into full hurricanes
Low Pressure

9. Must Come Down…………………………….The
Inter Tropical Convergence Zone and its
Relevance to Droughts

10. The Pressure Gradient Force
Very dry Lots of rain Very dry
Important points:
1. Air always moves from high pressure areas to low pressure areas
2. Low pressure areas are created at the ITCZ due to solar radiation causing evapotranspiration
3. Warming air can hold increasing amounts of water in vapor form and vice versa

11. Global Arid Areas
Notice that, in Africa, the arid and hyper-arid areas are in the areas where the subtropical high
pressure zones can be found. The effect of the ITCZ on Africa is particularly strong and as our
drought case study is on Ethiopia, particularly relevant
Drought causes are complex and so the movement of the ITCZ does not explain all drought.
Other important factors are ocean currents and continentality.