Understanding Global Climate The Inter Tropical Convergence Zone and its Relevance to Droughts and Hurricanes
What Goes Up…………………………….TheInter Tropical Convergence Zone and itsRelevance to Hurricanes
The ICTZ is the band of cloud that you can see here; it wraps the whole way aroundthe Earth underneath the solar equator
The ITCZ and HurricanesThe 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 thefirst stage of hurricane formation; the development of low pressure areas. Low pressure at surface
Summer in the Northern Hemisphere is when the sun is directly Summer inover the Tropic of Cancer the Southern Hemisphere is when the sun is directly over the Tropic of Capricorn
The movement of the ITCZ as the seasons change has a huge influence over global climate asthe weather associated with the ITCZ migrates with it.
You should be able to see that oceans north of the Equator are currently hotter than thosesouth 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 thenorthern hemisphere at the moment Equator
The movement of the solar equator (and thus the ITCZ) is crucial for the formation of hurricanesfor 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
Must Come Down…………………………….TheInter Tropical Convergence Zone and itsRelevance to Droughts
The Pressure Gradient Force Very dry Lots of rain Very dryImportant points:1. Air always moves from high pressure areas to low pressure areas2. Low pressure areas are created at the ITCZ due to solar radiation causing evapotranspiration3. Warming air can hold increasing amounts of water in vapor form and vice versa
Global Arid AreasNotice that, in Africa, the arid and hyper-arid areas are in the areas where the subtropical highpressure zones can be found. The effect of the ITCZ on Africa is particularly strong and as ourdrought case study is on Ethiopia, particularly relevantDrought causes are complex and so the movement of the ITCZ does not explain all drought.Other important factors are ocean currents and continentality.